JP3344044B2 - Polyglycerin fatty acid ester composition and method for producing oil-in-water emulsion using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyglycerol fatty acid ester composition generally used as an emulsifier for foods, pharmaceuticals, cosmetics and other industrial uses, and to an emulsification method using the same.

[0002]

2. Description of the Related Art Polyglycerin fatty acid esters are used as surfactants (emulsifiers) in foods, pharmaceuticals, cosmetics and the like. Polyglycerin fatty acid esters are important properties of surfactants by controlling the degree of polymerization of polyglycerin and the esterification of fatty acids bonded to it, and represent the ratio of the hydrophilic part to the lipophilic part in the molecule. HL
B can be changed.

A method for producing a polyglycerin fatty acid ester is as follows.
After polycondensation at a high temperature of 00 ° C. or more, polyglycerin is obtained by performing purification such as desalting and decolorization, and then, in the presence of an alkali catalyst, is reacted with various fatty acids or fatty acid esters under normal pressure or reduced pressure at a reaction temperature of 200 to The method of esterification at 240 ° C. is common.

The control of HLB in the synthesis of polyglycerin fatty acid ester is carried out by controlling the ratio of fatty acid and polyglycerin to be used for the reaction. For example, in order to obtain a high HLB, generally, polyglycerin having an average degree of polymerization of 6 or more is used, and the amount of the fatty acid charged in the reaction is controlled to an equimolar or less with respect to the polyglycerin. However, since this reaction is an esterification reaction, the final reactants will be of equilibrium composition, including those with varying degrees of esterification. Therefore, when trying to obtain a hydrophilic polyglycerin fatty acid ester, it is inevitable that unreacted polyglycerin remains.

[0005] Polyglycerin is one type of polyhydric alcohol containing an ether bond in the molecule, and has no function as a surfactant. Therefore, the reaction product containing unreacted polyglycerin is less effective as a surfactant per unit weight. Further, polyglycerin has high hydrophilicity and has a function as a cosurfactant or a hydrotrope. Therefore, a polyglycerin fatty acid ester containing the same has good water solubility but poor oil solubility. Therefore, when used as an emulsifier, there is a restriction that it must be added to the aqueous phase.

[0006]

The polyglycerin fatty acid ester is generally used by directly using a reaction product containing unreacted polyglycerin or by removing a coloring component or an odor component by steam distillation or the like. Has been offered to. Therefore, the conventional polyglycerin fatty acid ester called high HLB was always a composition containing a large amount of free polyglycerin. These conventional high HL
The polyglycerin fatty acid ester product of B has poor uniform dissolution and dispersibility in oil, which is a basic requirement for a phase inversion emulsification method in which an emulsifier is dispersed and solubilized in an oily component. It was said that this was not suitable for the phase inversion emulsification method because a gel-like insoluble matter was generated. In order to increase the dispersibility in oil, the molar ratio of the charged fatty acid during the polyglycerin fatty acid ester synthesis reaction may be increased, but in this case, a highly hydrophilic polyglycerin fatty acid ester cannot be obtained, so that the stable No oil-in-water emulsion can be produced. The present invention provides a polyglycerol fatty acid ester composition having high hydrophilicity and dispersibility in oil, and a method for obtaining a stable oil-in-water emulsion by phase inversion emulsification using the composition. .

[0007]

According to the present invention, polyglycerol having an average degree of polymerization of 4 or more is a fatty acid having 8 to 24 carbon atoms.
Of the total hydroxyl groups of the polyglycerin
Esters such that the average esterification rate is 15 to 50%
Made of polyglycerin fatty acid ester
And free polyglycerin is converted to polyglycerin fatty acid ester.
Free polyglycerin and free polyglycerin
Containing as the ratio of Li glycerin is 20 wt% or less
By dispersing and dissolving the polyglycerin fatty acid ester composition which may be dispersed in the oil phase, adding an aqueous phase thereto and inverting the continuous phase from the oil phase to the aqueous phase, thereby forming a stable oil-in-water emulsion. Obtainable. Thereby, a more stable oil-in-water emulsion can be obtained as compared with the conventional oil-in-water emulsion method in which the polyglycerin fatty acid ester is dissolved in the aqueous phase and the oil phase is added thereto.

Hereinafter, the present invention will be described in detail. As the polyglycerin constituting the polyglycerin fatty acid ester composition of the present invention, those having an average degree of polymerization of 4 or more are used. In particular, for use in foods, those having an average degree of polymerization of 4 to 12, for which safety and toxicity have been confirmed, are preferred. On the other hand, as the fatty acid to be reacted with polyglycerin, a linear or branched saturated or unsaturated fatty acid having 8 to 24 carbon atoms is suitable. These fatty acids can be used alone or in combination of two or more depending on the purpose. Examples of such fatty acids include lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, ricinoleic acid, isostearic acid, 2-ethylhexanoic acid, and the like.

The degree of esterification of the polyglycerin fatty acid ester is expressed as a percentage (average esterification rate) of the average number of ester bonds to the average total number of hydroxyl groups per polyglycerin molecule. Here, the average total number of hydroxyl groups is represented by (n + 2) when the average degree of polymerization obtained from the hydroxyl value of polyglycerin is n.

In the present invention, the average esterification rate of the polyglycerol fatty acid ester is 15 to 50%, preferably 1 to 50%.
5 to 30%. When the average esterification rate is 15% or less, the HLB of the polyglycerol fatty acid ester is too high, so that the oil solubility is reduced and good dispersion solubility in the oil phase cannot be obtained. Conversely, if it exceeds 50%, the oil solubility is improved, but the HLB is reduced, so that a stable oil-in-water emulsion cannot be obtained.

The free polyglycerin content contained in the polyglycerin fatty acid ester composition of the present invention is not more than 20% by weight, preferably 10% by weight, based on the total of the polyglycerin fatty acid ester and the free polyglycerin.
It is as follows. If the amount of free polyglycerin exceeds 20% by weight, a gel precipitate is formed when added to the oil phase, and a uniform dispersion and dissolution state in the oil phase cannot be obtained, and phase inversion emulsification cannot be performed.

The polyglycerin fatty acid ester composition according to the present invention can be produced by reacting polyglycerin with a fatty acid or a fatty acid ester, and then removing unreacted polyglycerin from the reaction product. Usually, glycerin is subjected to polycondensation at a high temperature of 200 ° C. or higher in the presence of an alkali catalyst, followed by purification such as desalting and decoloring to obtain polyglycerin. Next, various fatty acids or fatty acid esters or fats and oils are esterified or transesterified at a temperature of about 200 to 240 ° C. in the presence of an alkali catalyst. In this case, the reaction molar ratio of the fatty acid to polyglycerin may be usually 5 or less, but when the average degree of polymerization of polyglycerin is 6 or less, it is preferable to lower the molar ratio of the fatty acid to be charged. When the charged molar ratio exceeds 5, the average substitution ratio of the resulting polyglycerol fatty acid ester easily exceeds 50 mol%, and the high HL
B is difficult to obtain. Further, the reaction product contains impurities such as a catalyst and a small amount of a fatty acid salt derived from the raw material fatty acid. If polyglycerin and the polyglycerol fatty acid ester satisfy the composition of the present invention, the reaction product is purified without particular purification. Can be used for the purpose of the invention.

In general, the higher the HLB of the reaction product obtained by the above reaction, the higher the unreacted polyglycerin content. Therefore, in order to reduce the free polyglycerin content to 20% by weight or less, polyglycerin is removed from the reaction product by liquid-liquid extraction, adsorption separation, or the like. If necessary, polyglycerin may be separately added. Liquid-liquid extraction
The reaction is performed using a water-insoluble organic solvent such as isobutyl alcohol, methyl ethyl ketone, and ethyl acetate, and water. Since the polyglycerin fatty acid ester is selectively distributed to the temporary solvent phase and the polyglycerin is selectively distributed to the aqueous phase, it is possible to recover the unreacted polyglycerin fatty acid ester having a reduced unreacted polyglycerin content from the organic solvent phase. I can do it. However, the number of extraction stages is often insufficient with one stage, and multistage extraction is usually performed.

In the adsorption separation, an esterification reactant dissolved in a water-containing organic solvent is brought into contact with an adsorbent to selectively adsorb the polyglycerol fatty acid ester, and is separated from unreacted polyglycerin. This is a method in which glycerin fatty acid ester is eluted from an adsorbent with an eluent and recovered. As the adsorbent, an inorganic adsorbent such as an alkylsilylated silica gel represented by octadecylated silica gel (ODS), a synthetic adsorbent such as a styrene-divinylbenzene copolymer and a polymethacrylic acid ester are used. As the organic solvent, a solvent such as acetone, methanol, ethanol, isopropanol, methyl ethyl ketone, and acetonitrile, which is mixed with water at an arbitrary ratio is used. These may be used alone or as a mixture of two or more. However, when the obtained polyglycerin fatty acid ester composition is used for food, it is preferable to use a lower alcohol such as methanol or ethanol from the viewpoint of safety. Further, in this method, a polyglycerol fatty acid ester containing very little free polyglycerin is often obtained, so that the composition is adjusted to a predetermined range by adding polyglycerin, if desired.

The polyglycerin fatty acid ester composition whose unreacted polyglycerin content is reduced to 20% by weight or less by such extraction or adsorptive separation is characterized by being hydrophilic and being easily dispersed and dissolved in oil. Addition of an emulsifier to an oil phase during preparation of an oil-in-water emulsion is effective for stabilizing emulsification and reducing the amount of emulsifier used. When the polyglycerol fatty acid ester composition according to the present invention is used, a so-called phase-inversion emulsification method in which an oil-in-water emulsion is obtained by previously setting a water-in-oil emulsion state and then further adding an aqueous phase is possible. According to this method, fine droplets are formed, and a stable emulsified state is obtained. Further, since the content of free polyglycerin is small, the use of a fatty acid having a melting point of room temperature or higher results in a product with no stickiness and excellent operability.

[0016]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the scope of the invention. Quantification of polyglycerin: Quantification of free polyglycerin was performed by high performance liquid chromatography under the following conditions.

[0017]

Table 1 << Conditions for high-performance liquid chromatography analysis >> Apparatus Shimadzu LC-10AD system Column Reversed phase column YMC-AM (6.0 mmφ)
× 150 mm) GPC column Asahipak GS310H (6.
0 mmφ × 300 mm) 2 Column temperature 40 ° C. Mobile phase Methanol / water = 30/70 Detector Differential refractometer (Shimadzu RID-6A) Sample THF / methanol = 6/4 dissolved in solution.
Injection volume = 50 μl

A reversed-phase packing column and a gel permeation (GPC) column are connected in series, and a sample is injected into the reversed-phase packing column. Polyglycerin fatty acid esters are selectively adsorbed to the reversed-phase column, but polyglycerin is eluted without being adsorbed. The eluted polyglycerin and low molecular impurities are introduced into a GPC column and separated. The quantification is performed using a differential refractometer as a detector and an absolute calibration curve of polyglycerin prepared in advance. Thereby, the content of unreacted polyglycerin in the esterification reaction product can be easily determined.

Average esterification rate: The average esterification rate of polyglycerol fatty acid ester is as follows, where n is the average degree of polymerization of polyglycerin, and the average total number of hydroxyl groups per molecule is (n + 2). It is defined by the following formula as a percentage of the number of ester bonds.

[0020]

(Equation 1) FA: Samples saponification, recovered fatty acid weight (g) M _FA: Molecular weight of the fatty acid POG _E: Samples saponification, recovered polyglycerol weight (g) M _POG: molecular weight of the polyglycerol (M _POG = 74n
+18) n: average degree of polymerization of polyglycerin

The esterification rate of the polyglycerin fatty acid ester is determined from the amounts of fatty acids and polyglycerin obtained by saponifying the polyglycerin fatty acid ester composition based on the above formula. If the sample contains unreacted polyglycerin, the content of unreacted polyglycerin in the sample needs to be determined in advance, and this amount needs to be subtracted.

HLB: HLB was calculated by the Griffin equation. In the following formula, the hydrophilic portion refers to a portion obtained by removing the fatty acid hydrocarbon chain from the whole polyglycerin fatty acid ester molecule.

[0023]

(Equation 2)

Example 1 A reaction vessel was charged with 825 g (1 mol) of polyglycerin (average degree of polymerization 11), 275.6 g (1 mol) of stearic acid, and 0.03 g of sodium hydroxide, and heated at 220 ° C. under a nitrogen stream. After reacting for 3 hours, the pale yellow semi-solid
83 g were obtained. The unreacted polyglycerin content of the obtained product was determined by high performance liquid chromatography as described above.
2.5% by weight. Unreacted polyglycerin was separated and removed from the reaction product under the following conditions, and a pale yellow solid 62
0 g was obtained.

<< Separation Conditions >> A synthetic adsorbent Diaion® HP-2MG (manufactured by Mitsubishi Kasei Co., Ltd.) was charged into a glass column filled with 1 liter by a wet method, and 25 g of a reaction product was added to 50 ml of a 30% by volume aqueous ethanol solution. Supply the dissolved solution. Next, the same solvent is sent by SV2 to elute unreacted polyglycerin in the reaction product. 100 more
% Ethanol is sent, and the adsorbed polyglycerol fatty acid ester is eluted and collected as an ethanol solution.
This solution is concentrated under reduced pressure to obtain a polyglycerin fatty acid ester. The analysis values of the obtained polyglycerin fatty acid ester were as follows.

[0026]

[Table 2] << Analysis value >> Unreacted polyglycerin = 0.2%
Below Average esterification rate = 21.1% Calculated HLB = 11.9

The same polyglycerin as used for the reaction was mixed with this polyglycerin fatty acid ester to prepare a polyglycerin fatty acid ester composition having a polyglycerin content shown in Table 1. 3% of this composition based on rapeseed oil
It was added and its solubility in rapeseed oil was examined. The results are shown in Table 1.

[0028]

[Table 3]

Although the obtained polyglycerin fatty acid ester is hydrophilic (calculated HLB = 11.9), it can be dissolved and dispersed in oil, but if the unreacted polyglycerin content exceeds 20%, rapeseed oil It was found that the solubility in oil decreased, and uniform dissolution and dispersion in oil could not be obtained.

Example 2 An aqueous phase was added to a solution of the polyglycerin fatty acid ester obtained in Example 1 in an oil phase, and an oil-in-water emulsion was obtained by a phase inversion emulsification method. For comparison, an oil-in-water emulsion having the same composition was prepared by an ordinary method of adding an oil phase to a solution in which a polyglycerin fatty acid ester was dissolved in an aqueous phase. A comparison was made of the emulsion stability of both oil-in-water emulsions.

The formulation of the emulsification was as follows.

Table 4 Polyglycerin fatty acid ester 1.0 g Salt 5.0 g Acetic acid 0.2 g Water 75.0 g Rapeseed oil 18.8 g

Phase inversion emulsification method: polyglycerin fatty acid ester was dispersed and dissolved in rapeseed oil at 70 ° C.
While stirring at pm, 10 g of 70 ° C. water was slowly added. Then the remaining aqueous phase containing salt and acetic acid was added,
Stir for a total of 10 minutes. The obtained emulsion was immediately cooled to room temperature and subjected to a storage test at 30 ° C.

Normal emulsification method: polyglycerin fatty acid ester, salt and acetic acid are dispersed and dissolved in water at 70 ° C.
Rapeseed oil at 70 ° C. was slowly added while stirring at 000 rpm, and the mixture was stirred for a total of 10 minutes. The obtained emulsion was immediately cooled to room temperature and subjected to a storage test at 30 ° C.
The stability of the emulsion was evaluated based on the water separation defined by the following equation. Table 2 shows the results. The smaller the water separation rate, the more stable the emulsification.

[0034]

(Equation 3)

[0035]

[Table 5]

In the emulsion obtained by the ordinary method, a large amount of aqueous phase separation is observed in a short time, but in the case of the phase inversion method, the degree of aqueous phase separation is small.

[0037]

The polyglycerin fatty acid ester composition according to the present invention has a markedly improved tackiness, unlike the conventional high HLB polyglycerin fatty acid ester. When producing an oil-in-water emulsion by the phase inversion emulsification method,
The dispersibility of the polyglycerin fatty acid ester in the oil component is improved, and good emulsification becomes possible.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-37710 (JP, A) JP-A-4-208248 (JP, A) JP-A-59-62340 (JP, A) JP-A-2- 138107 (JP, A) JP-A-7-145104 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 71/02-71/03 A61K ⁷ /00-7/50 C07C 69/67-69/72 A23L 1/035 WPI (DIALOG)

Claims (4)

(57) [Claims] 1. Polyglycerin having an average degree of polymerization of 4 or more ,
A fatty acid having 8 to 24 carbon atoms forms an ester by
The average esterification rate of the total hydroxyl groups of glycerin is 15 to 5
Polyglycerin esterified to 0%
Free polyglycerin consisting of fatty acid esters
Of polyglycerol fatty acid ester and free polyglycerol
The ratio of free polyglycerin to the total with phosphorus is 2
A polyglycerin fatty acid ester composition, which may be contained so as to be 0% by weight or less. 2. The method of claim 1, wherein the free polyglycerol is polyglycerol.
Occupied by the sum of fatty acid esters and free polyglycerin
Of free polyglycerol to be less than 10% by weight.
2. The composition according to claim 1, wherein the composition is contained in such a manner that
The polyglycerin fatty acid ester composition as described in the above. 3. The polyglycerin fatty acid ester is
Average Esters of Total Hydroxyl Groups of Polyglycerol Constituting Ter
Esterified so that the degree of esterification is 15 to 30%.
3. The method according to claim 1, wherein
Polyglycerin fatty acid ester composition. 4. A continuous phase is converted from an oil phase to an aqueous phase by adding an aqueous phase to an oil phase in which the composition according to claim 1 is dispersed and dissolved. A method for producing an oil-in-water emulsion.