Method for producing composition comprising alkali metal salt of ascorbyl 2-glucoside and basic amino acid salt of ascorbyl 2-glucoside

Abstract

To provide a method for producing a stable composition comprising an alkali metal salt of ascorbyl 2-glucoside and a basic amino acid salt of ascorbyl 2-glucoside without browning.SOLUTION: The present invention provides a method for producing a composition comprising an alkali metal salt of ascorbyl 2-glucoside and a basic amino acid salt of ascorbyl 2-glucoside that involves adding an alkali metal bicarbonate or an alkali metal carbonate to an ascorbyl 2-glucoside aqueous solution, and then adding a basic amino acid to adjust the pH to 5-8.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for producing a stable composition containing an alkyl metal salt of ascorbic acid 2-glucoside and a basic amino acid salt of ascorbic acid 2-glucoside. [Background technology]

[0002] Ascorbic acid acts as a reducing agent, a collagen synthesis promoter, and an antioxidant. In particular, the excellent antioxidant effect of ascorbic acid suppresses melanin production in the skin and is known as an ingredient that prevents pigmentation such as age spots and freckles, and is widely incorporated into medicines, foods, cosmetics, etc. However, ascorbic acid is unstable in its raw powder form when it is hygroscopic or alkaline, and an aqueous solution of ascorbic acid is not only highly acidic and irritating, but also easily oxidizes and browns due to the Maillard reaction caused by typical amines involved in decomposition, and the browning reaction progresses. For these reasons, cosmetics containing ascorbic acid and products containing water are prone to browning and develop unpleasant odors, losing their value as a product, and the amount of ascorbic acid added to the product is restricted, which inevitably affects its effectiveness (Non-Patent Document 1). From this perspective, a technique of blending flavonoid glycosides with ascorbic acid to suppress browning of ascorbic acid has been reported (Patent Documents 1 and 2). It has also been reported that ascorbic acid 2-glucoside is used instead of ascorbic acid.

[0003] However, the aqueous solution of ascorbic acid 2-glucoside has a low pH and, although its stability is improved slightly, the drawback of browning remains. Therefore, techniques of blending a strong base, lecithin, an ether compound, an ester compound, citric acid, etc. with ascorbic acid 2-glucoside have been reported (Patent Documents 3 to 6). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 04-099771 [Patent Document 2] Japanese Patent Application Publication No. 04-099730 [Patent Document 3] JP 2001-199863 A [Patent Document 4] JP 2002-265344 A [Patent Document 5] JP 2005-220029 A [Patent Document 6] JP 2012-246248 A [Non-patent literature]

[0005] [Non-Patent Document 1] Journal of the Japanese Society for Food and Nutrition, Vol. 26, No. 1, 7-10 (2015) Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a method for producing a stable composition containing an alkali metal salt of ascorbic acid 2-glucoside and a basic amino acid salt of ascorbic acid 2-glucoside which does not undergo browning. [Means for solving the problem]

[0007] Therefore, the present inventors conducted various investigations to produce a stable composition containing an alkali metal salt of ascorbic acid 2-glucoside and a basic amino acid salt of ascorbic acid. As a result, they found that a composition containing an alkali metal salt of ascorbic acid 2-glucoside and a basic amino acid salt of ascorbic acid that has a stable pH after neutralization and does not brown can be obtained by first adding an alkali metal hydrogencarbonate or an alkali metal carbonate to an aqueous solution of ascorbic acid 2-glucoside, and then adding a basic amino acid to adjust the pH to 5 to 8, thereby completing the present invention.

[0008] That is, the present invention provides the following inventions [1] to [4]. [1] A method for producing a composition containing an alkali metal salt of ascorbic acid 2-glucoside and a basic amino acid salt of ascorbic acid, comprising adding an alkali metal hydrogencarbonate or an alkali metal carbonate to an aqueous solution of ascorbic acid 2-glucoside, and then adding a basic amino acid to adjust the pH to 5 to 8. [2] The method according to [1], wherein the molar ratio (a / b) of the alkali metal salt of ascorbic acid 2-glucoside (a) to the basic amino acid salt of ascorbic acid (b) in the composition containing the alkali metal salt of ascorbic acid 2-glucoside and the basic amino acid salt of ascorbic acid is 0.1 or more and 1 or less. [3] The method according to [1] or [2], in which the reaction is carried out while introducing nitrogen gas into an aqueous solution of ascorbic acid 2-glucoside. [4] The method according to any one of [1] to [3], wherein the pH is adjusted to 5 to 7. Effect of the Invention

[0009] According to the method of the present invention, a composition containing an alkali metal salt of ascorbic acid 2-glucoside and a basic amino acid salt of ascorbic acid can be obtained, which has a stable pH after neutralization and does not brown. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Terms used in this specification are used in the same manner as commonly used in the art unless otherwise specified.

[0011] In this specification, "ascorbic acid" is an organic compound named (R)-3,4-dihydroxy-5-((S)-1,2-dihydroxyethyl)furan-2(5H)-one in the IUPAC nomenclature system, which acts as vitamin C for humans and is used as an antioxidant food additive. In addition, the excellent antioxidant effect of ascorbic acid is known as an ingredient that inhibits melanin production in the skin and prevents pigmentation such as age spots and freckles, and is widely used in cosmetics. In this specification, "ascorbic acid 2-glucoside" is a compound in which glucose is bound to the carbon at the 2nd position of ascorbic acid, and is an ascorbic acid derivative with improved stability. It is approved as an active whitening ingredient in quasi-drugs and as a food additive. It is also called stable vitamin C or sustained-release vitamin C.

[0012] In the present specification, the term "alkali metal" refers to an element belonging to Group 1 of the periodic table excluding hydrogen, and includes lithium, sodium, potassium, rubidium, cesium, and francium. In the present invention, sodium and potassium are preferred, and sodium is more preferred.

[0013] In this specification, the term "alkali metal hydrogen carbonate" refers to a hydrogen carbonate of the alkali metal. Specific examples include sodium hydrogen carbonate and potassium hydrogen carbonate, with sodium hydrogen carbonate being more preferred. The "alkali metal carbonate" is a carbonate of the alkali metal. Specific examples include sodium carbonate and potassium carbonate, with sodium carbonate being more preferred.

[0014] As used herein, the term "basic amino acid" refers to a polar amino acid that is positively charged at neutral pH and has an amino group in the side chain. Examples of basic amino acids include lysine, arginine, and histidine, with arginine being particularly preferred in the present invention.

[0015] In this specification, "pH" refers to the hydrogen ion concentration index of an aqueous solution, and can be measured using a commercially available pH meter. "Dissolved oxygen concentration" is also called the amount of dissolved oxygen, and can be measured using a commercially available dissolved oxygen meter.

[0016] One aspect of the present invention is a method for producing a composition containing an alkali metal ascorbic acid 2-glucoside salt and a basic amino acid salt of ascorbic acid, the method comprising adding an alkali metal hydrogencarbonate or an alkali metal carbonate to an aqueous solution of ascorbic acid 2-glucoside, and then adding a basic amino acid to adjust the pH to 5 to 8.

[0017] The concentration of ascorbic acid 2-glucoside in the aqueous solution is not particularly limited, but is preferably from 1% by mass to 50% by mass.

[0018] In the present invention, it is preferable to introduce nitrogen gas into the aqueous solution of ascorbic acid 2-glucoside from the beginning in order to stabilize the pH after neutralization during the reaction. The rate of introduction of nitrogen gas into the aqueous solution is preferably 100 mL / min or more, more preferably 120 mL / min or more, and even more preferably 150 mL / min or more in order to prevent browning of the composition containing the obtained alkali metal salt of ascorbic acid 2-glucoside and basic amino acid salt of ascorbic acid 2-glucoside. In addition, the introduction of this nitrogen gas is preferably performed so that the dissolved oxygen concentration (DO) in the aqueous solution is 5 ppm or less, and more preferably 4 ppm or less. The method of introducing nitrogen gas into the aqueous solution is preferably performed by blowing nitrogen gas into the aqueous solution. In addition, it is preferable to introduce nitrogen gas into the aqueous solution until the end of the reaction, that is, until the end of the adjustment of the pH to 5 to 8.

[0019] In the present invention, first, an alkali metal hydrogen carbonate or an alkali metal carbonate is added to an aqueous solution of ascorbic acid 2-glucoside. The alkali metal hydrogen carbonate to be added is preferably sodium hydrogen carbonate or potassium hydrogen carbonate, more preferably sodium hydrogen carbonate.The alkali metal carbonate to be added is preferably sodium carbonate or potassium carbonate, more preferably sodium carbonate. The rate of addition of the alkali metal hydrogen carbonate or the alkali metal carbonate is preferably gradual so as not to cause a large change in pH. The amount of the alkali metal hydrogen carbonate or the alkali metal carbonate added is preferably 0.1 mol or more and 0.5 mol or less per mol of ascorbic acid 2-glucoside from the viewpoint of stabilizing the pH after the neutralization reaction.

[0020] Next, a basic amino acid is added to adjust the pH to 5-8. The basic amino acid to be added is preferably arginine, lysine or histidine, more preferably arginine. The basic amino acid is added until the pH of the aqueous solution is stabilized between 5 and 8. The basic amino acid is preferably added gradually so that the pH does not fluctuate significantly. The amount of the basic amino acid added is until the pH of the aqueous solution is stabilized between 5 and 8, and is preferably 0.5 mol to 0.9 mol per mol of ascorbic acid 2-glucoside from the viewpoint of stabilizing the pH after the neutralization reaction. The pH is preferably 5 to 7, more preferably 5 to 6, and even more preferably 5.0 to 5.5. The above reaction is preferably carried out under atmospheric pressure at room temperature, for example, from 5°C to 40°C.

[0021] The resulting composition containing an alkali metal salt of ascorbic acid 2-glucoside and a basic amino acid salt of ascorbic acid is desirably neutralized as a composition (mixture), and the molar ratio (a / b) of the alkali metal salt of ascorbic acid 2-glucoside (a) to the basic amino acid salt of ascorbic acid (b) in the composition is preferably 0.1 or more and 1 or less.

[0022] After completion of the reaction, the resulting aqueous solution containing the alkali metal salt of ascorbic acid 2-glucoside and the basic amino acid salt of ascorbic acid may be used as is, or it can be isolated as a powder containing the alkali metal salt of ascorbic acid 2-glucoside and the basic amino acid salt of ascorbic acid by freeze-drying.

[0023] The obtained aqueous solution containing an alkali metal salt of ascorbic acid 2-glucoside and a basic amino acid salt of ascorbic acid or the powder containing an alkali metal salt of ascorbic acid and a basic amino acid salt of ascorbic acid does not turn brown even when stored for a long period of time and is stable. In addition, the aqueous solution containing an alkali metal salt of ascorbic acid 2-glucoside and a basic amino acid salt of ascorbic acid does not change in pH and is stable. Therefore, the aqueous solution containing an alkali metal salt of ascorbic acid 2-glucoside and a basic amino acid salt of ascorbic acid or the powder containing an alkali metal salt of ascorbic acid 2-glucoside and a basic amino acid salt of ascorbic acid obtained by the method of the present invention can be widely used in cosmetics, medicines, foods, etc. EXAMPLES

[0024] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples in any way.

[0025] Comparative Example 1 (Na salt only) 200 g of purified water was weighed into a 500 mL glass beaker. 34.2 g (0.1 M) of ascorbic acid 2-glucoside powder (molecular weight 338.26) was weighed and gradually added to the beaker while stirring with a magnetic stirrer, and completely dissolved at room temperature. 8.4 g (0.1 M) of sodium bicarbonate powder (molecular weight 84.007) was gradually added to the beaker and stirred with a magnetic stirrer. The pH of the solution immediately after dissolution was 4.993. The pH after 60 minutes was 5.365, an increase of 0.372 was observed.

[0026] Example 1 (Preparation of Na salt and arginine salt simultaneously) (sodium bicarbonate:arginine = approximately 1:3) 200 g of purified water was weighed into a 500 mL glass beaker. 34.2 g (0.1 M) of powder of ascorbic acid 2-glucoside (molecular weight 338.26) was weighed and gradually added to the beaker while stirring with a magnetic stirrer, and completely dissolved at room temperature. 2.1 g (0.025 M) of powder of sodium bicarbonate (molecular weight 84.007) was gradually added to the beaker and stirred with a magnetic stirrer. After this, 13.71 g (0.08 M) of powder of arginine (molecular weight 174.2) was added and stirred with a magnetic stirrer until completely dissolved. The pH of the solution immediately after dissolution was 5.034. The pH after 60 minutes was 5.058, with almost no change.

[0027] Example 2 (Preparation of Na salt and arginine salt simultaneously) (sodium bicarbonate:arginine = approximately 1:1) 200 g of purified water was weighed into a 500 mL glass beaker. 34.2 g (0.1 M) of ascorbyl glucoside (molecular weight 338.26) powder was weighed and gradually added to the beaker while stirring with a magnetic stirrer, and completely dissolved at room temperature. 4.2 g (0.05 M) of sodium bicarbonate (molecular weight 84.007) powder was gradually added to the beaker and stirred with a magnetic stirrer. After this, 9.06 g (0.052 M) of arginine (molecular weight 174.2) powder was added and stirred with a magnetic stirrer until completely dissolved. The pH of the solution immediately after dissolution was 5.058. The pH after 60 minutes was 5.070, with almost no change. The calculated solids content was 34.2+4.2+9.06=47.46g. The entire amount of the prepared solution was transferred to a plastic tray and freeze-dried using a freeze dryer to obtain 47.4 g of a white dry powder. The solid recovery rate was 99.9%. The NMR of the obtained powder was measured and it was confirmed that it was a mixture of ascorbic acid 2-glucoside sodium salt and ascorbic acid 2-glucoside arginine salt.

[0028] Example 3 (with N2 purging from the beginning) 200 g of purified water was weighed into a 500 mL glass beaker. 34.2 g (0.1 M) of powder of ascorbyl glucoside (molecular weight 338.26) was weighed and gradually added to the beaker while stirring with a magnetic stirrer, and completely dissolved at room temperature. 2.1 g (0.025 M) of powder of sodium bicarbonate (molecular weight 84.007) was gradually added to the beaker and stirred with a magnetic stirrer. After this, 13.71 g (0.08 M) of powder of arginine (molecular weight 174.2) was added and stirred with a magnetic stirrer until completely dissolved. From the beginning of the operation, pure nitrogen gas was blown into the solution at a flow rate of 150 mL / min from a nitrogen cylinder via a regulator, and the nitrogen gas was stopped at the stage where the pH adjustment was completed. The pH of the solution immediately after dissolution was 5.020. The pH after 60 minutes was 5.055 and showed little change.

[0029] Comparative Example 2 (without N2 purging) 200 g of purified water was weighed into a 500 mL glass beaker. 34.2 g (0.1 M) of ascorbyl glucoside (molecular weight 338.26) powder was weighed and gradually added to the beaker while stirring with a magnetic stirrer, and completely dissolved at room temperature. 2.1 g (0.025 M) of sodium bicarbonate (molecular weight 84.007) powder was gradually added to the beaker and stirred with a magnetic stirrer. After this, 13.71 g (0.08 M) of arginine (molecular weight 174.2) powder was added and stirred with a magnetic stirrer until completely dissolved. The pH of the solution immediately after dissolution was 5.030. The pH after 60 minutes was 5.061, with almost no change.

[0030] Table 1 shows the changes in pH and dissolved oxygen concentration (DO) over time.

[0031] [Table 1]

[0032] The stability after pH adjustment was good in both Comparative Example 2 and Example 3. In Example 3, in which N2 purging was performed from the beginning, the final DO was lower than that in Comparative Example 2.

Claims

1. A method for producing a composition containing an alkali metal ascorbic acid 2-glucoside salt and a basic amino acid salt of ascorbic acid, comprising adding an alkali metal hydrogencarbonate or an alkali metal carbonate to an aqueous solution of ascorbic acid 2-glucoside, and then adding a basic amino acid to adjust the pH to 5 to 8.

2. 2. The method according to claim 1, wherein the molar ratio (a / b) of the alkali metal salt of ascorbic acid 2-glucoside (a) to the basic amino acid salt of ascorbic acid (b) in the composition containing the alkali metal salt of ascorbic acid 2-glucoside and the basic amino acid salt of ascorbic acid is 0.1 or more and 1 or less.

3. The process according to claim 1 or 2, wherein the reaction is carried out while introducing nitrogen gas into the aqueous solution of ascorbic acid 2-glucoside.

4. The process according to any one of claims 1 to 3, wherein the pH is adjusted to 5 to 7.

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