JP7733985B2 - Porphyran particles, method for producing the same, and cosmetics - Google Patents

Description

The present invention relates to Porphyran particles formed by the aggregation of Porphyran with good biodegradability, and in particular to spherical Porphyran particles and cosmetics containing the same.

Petroleum-derived synthetic polymers (plastics) are currently used in a variety of industries. Many synthetic polymers were developed with the goal of long-term stability, and therefore do not decompose in the natural environment. This has led to a variety of environmental problems. For example, plastic products that have been released into the aquatic environment accumulate over long periods of time, causing significant harm to the ecosystems of oceans and lakes. In recent years, microplastics, tiny pieces of plastic measuring less than 5 mm in length down to the nano-level, have become a major problem. Examples of microplastics include fine particles found in cosmetics, small clumps of plastic resin before processing, and larger products that break down into smaller pieces as they float in the ocean.

In recent years, plastic particles (e.g., polyethylene particles) on the order of several hundred microns have been blended into cosmetics to improve their texture characteristics. Because plastic particles have a low true specific gravity, they are difficult to remove at sewage treatment plants and are prone to flowing into rivers, oceans, ponds, and other areas. Furthermore, because plastic particles tend to adsorb chemicals such as pesticides, there is a risk that they may have an adverse effect on the human body due to bioaccumulation. This has been pointed out by the United Nations Environment Programme and other organizations, and various countries and industry groups are considering regulating them.

In addition, interest in natural and organic cosmetics is growing, and guidelines for labeling the natural/organic index for cosmetics (ISO 16128) have been established. According to these guidelines, the ingredients in a product are classified into, for example, natural ingredients, naturally derived ingredients, and non-natural ingredients, and an index is calculated based on the content of each ingredient. In the future, indexes will be displayed on products in accordance with these guidelines, so naturally derived ingredients and even more natural ingredients will likely be required.

Against this backdrop, biodegradable plastics are attracting attention. These plastics are decomposed into water and carbon dioxide by microorganisms in the natural environment and are integrated into the natural carbon cycle. In particular, cellulose particles, a natural plant-derived raw material, do not float on water even if released into the environment. Furthermore, due to their good biodegradability, there is little concern that they will cause environmental problems. Powdered cellulose particles with strength and disintegrability suitable for scrubbing agents are known, using cellulose obtained through a process that does not involve intentional chemical modification (see, for example, Patent Document 1). It is also known that type I crystalline cellulose particles are produced by granulating and drying cellulose dispersed in an organic solvent using a spray-drying method (see, for example, Patent Document 2). It is also known that the use of spherical composite particles containing type I crystalline cellulose and silica allows the production of cosmetics that combine tactile properties with environmental friendliness (see, for example, Patent Document 3).

Japanese Patent Application Laid-Open No. 2017-88873 Japanese Patent Application Publication No. 2-84401 WO2019/189692

However, the cellulose in the patent document is a trans-polysaccharide composed of glucose molecules, and is insoluble in water. For this reason, cellulose is not thought to be highly degradable in nature. Therefore, the object of the present invention is to create particles that provide excellent tactile properties using a highly biodegradable, water-soluble material.

In the present invention, porphyran has been used to create particles that provide excellent tactile properties. Porphyran is a type of trans-polysaccharide composed of galactose molecules, with some of the hydroxyl groups replaced with sulfate groups. This gives it high water solubility and biodegradability. Cosmetics formulated with particles formed from such porphyran pose fewer environmental concerns and can provide tactile properties similar to those of conventional plastic beads. The porphyran particles of the present invention are formed by aggregations of porphyran, a trans-polysaccharide composed of galactose molecules. The average particle size of the porphyran particles is 0.5 to less than 20 μm, and the protein content is less than 100 ppm.

The method for producing Porphyran particles according to the present invention comprises the steps of preparing a dispersion of Porphyran having a protein content of less than 100 ppm, and spray-drying the dispersion to granulate it, thereby obtaining a powder of Porphyran particles.

Any of the Porphyran particles described above can be combined with cosmetic ingredients to produce a cosmetic.

1 is an SEM photograph showing the appearance of the porphyran particles of Example 1.

The porphyran particles of the present invention are formed by aggregations of porphyran, a "trans-polysaccharide composed of galactose molecules," and have an average particle diameter d of 0.5 μm or more but less than 20 μm and a protein content of less than 100 ppm. The average particle diameter d affects the tactile properties of cosmetics. If the particle diameter is less than 0.5 μm, tactile properties such as rolling feel, duration of rolling feel, and uniform spreadability are significantly reduced. On the other hand, if the particle diameter exceeds 20 μm, the cosmetic product will feel rough and the soft and moist feel will be reduced. The average particle diameter d is preferably 1 to 20 μm, and optimally 1 to 15 μm.

Seaweed, the raw material for Porphyran, is rich in protein. It has been pointed out that even seaweed, a typical processed food, can occasionally cause food allergies. There are also concerns about unknown health hazards, such as food-dependent exercise-induced allergies caused by hydrolyzed wheat. For this reason, it is desirable to reduce the protein content by purifying the raw materials in advance. Therefore, the protein content in Porphyran particles is kept below 100 ppm. Less than 10 ppm is even more preferable. The protein content is determined using the Kjeldahl method.

Seaweed also has the ability to absorb arsenic. For this reason, Porphyran is said to contain tens to hundreds of ppm of arsenic. Therefore, for safety reasons, it is preferable to purify the porphyran before granulation to remove (reduce) the arsenic in advance. The arsenic content in Porphyran particles is preferably less than 5 ppm. If it contains 5 ppm or more, it may not be permitted to be used in cosmetics.

The sphericity of the Porphyran particles is preferably 0.85 or greater. Cosmetics containing particles with a sphericity of less than 0.85 do not provide good rolling properties. A sphericity of 0.90 or greater is particularly preferred.

Porphyran is known to have moisturizing power equivalent to that of hyaluronic acid. After leaving Porphyran particles standing for 12 hours under conditions of 40°C/90% RH, it is preferable that the moisture retention be 30% or more. When blended into cosmetics, this can prevent external irritation and dryness. A moisture retention of 50% or more is particularly preferable.

Here, the Porphyran content in the Porphyran particles is desirably 90% or more. 95% or more, more than 99%, and essentially 100% are particularly preferred. The higher the content, the higher the natural index according to the aforementioned guidelines. The Porphyran content (Porphyran content per solid content) can be measured using the phenol-sulfuric acid method and calculated from the concentration obtained using a calibration curve previously prepared using galactose.

Next, we will explain the method for producing porphyran particles.

First, a porphyran dispersion is prepared. Porphyran is found in large amounts in seaweed and can be obtained by known methods of extraction using hot water treatment (for example, JP 2005-120193 A). Alternatively, commercially available porphyran powder (manufactured by MMO Co., Ltd.) or porphyran extract (manufactured by Shirako Co., Ltd.) may also be used. When using porphyran powder, it is dispersed in warm water at a temperature of 70°C or higher but lower than 90°C. Dispersion is then promoted by irradiating with ultrasound. A uniform dispersion can be obtained by further adjusting the pH to between 8 and 10 using an aqueous alkaline solution. The solids concentration of this dispersion is then adjusted to a range of 1-7% to obtain a dispersion with the appropriate viscosity.

If the temperature of the hot water in which the Porphyran powder is dispersed is below 70°C, the Porphyran powder is likely to be insufficiently dispersed. As a result, the particles are less likely to become spherical during spray drying, resulting in low sphericity. Increasing the temperature of the hot water to 90°C or higher does not promote dispersion of the Porphyran powder, is economically unprofitable, and has no particular advantages. Furthermore, dispersion is also insufficient if ultrasonic irradiation is not performed. If the pH is adjusted using an alkaline aqueous solution to less than 8, dispersion is also insufficient. Increasing the pH to 10 or higher does not further promote dispersion, is economically unprofitable, and has no particular advantages. If the solids concentration exceeds 7%, the viscosity typically increases, making it impossible to form spherical droplets during spray drying, and the sphericity of the particles is likely to decrease. Furthermore, the droplets tend to become larger during spray drying, resulting in a larger particle size. A concentration of less than 1% is economically unprofitable and has no particular advantages. Water is the preferred solvent for the dispersion.

The Porphyran powder dispersion is then subjected to enzyme treatment using protease or the like, solvent extraction treatment using acetone or the like, or organic acid treatment using malic acid or the like. This reduces the protein content, making it possible to reduce the residual protein content to less than 100 ppm. These reduction treatments may also be combined.

It is also preferable to reduce the arsenic contained in the dispersion liquid. While the washing in the protein reduction treatment described above can reduce arsenic to some extent, it is difficult to reduce it to less than 5 ppm. Therefore, by using a strongly acidic cation exchange resin, arsenic can be removed from the dispersion liquid to less than 5 ppm. This arsenic reduction treatment can be carried out before the protein reduction treatment.

Next, the Porphyran dispersion with reduced residual protein is granulated using a spray dryer by spray drying. Protein and arsenic reduction treatment is performed prior to granulation. Porphyran particles are produced by spraying into a hot air stream at a rate of 1 to 3 liters per minute. Spraying can be performed using an atomizer, two-fluid nozzle, etc. The hot air preferably has an inlet temperature of 70 to 200°C and an outlet temperature of 40 to 60°C. If the inlet temperature is below 70°C, the solids contained in the dispersion will not dry sufficiently and will adhere to the inside of the device. If the temperature exceeds 200°C, the Porphyran may decompose. If the outlet temperature is below 40°C, the solids will not dry sufficiently and will adhere to the inside of the device. A more preferred inlet temperature is 130 to 190°C. In the case of a two-fluid nozzle, the spray air pressure for generating spray droplets can be adjusted within the range of 0.05 to 0.60 MPa depending on the desired particle size. If the spray air pressure is less than 0.05 MPa, it is difficult to obtain uniformly sprayed droplets, and some droplets will become too large to dry in the hot air stream and will adhere to the inside of the device. Exceeding 0.60 MPa does not further improve the spray quality and provides no particular advantage. When using an atomizer, the rotation speed can be adjusted between 3,000 and 30,000 rpm depending on the desired particle size. If the rotation speed is less than 3,000 rpm, it is difficult to obtain uniformly sprayed droplets, and some droplets will become too large to dry in the hot air stream and will adhere to the inside of the device. Exceeding 30,000 rpm does not further improve the spray quality and provides no particular advantage.

<Cosmetics>
Cosmetics can be obtained by blending the above-mentioned Porphyran particles with various cosmetic ingredients. Such cosmetics can simultaneously provide the same rolling feel, long-lasting rolling feel, and uniform spreadability as silica particles, as well as the same soft and moist feel as plastic beads. In other words, they can satisfy the typical tactile properties required of a cosmetic feel-improving agent.

Specific examples of cosmetics are listed by category in Table 1. These cosmetics can be manufactured using conventional methods known in the art. Cosmetics are available in a variety of forms, including powder, cake, pencil, stick, cream, gel, mousse, liquid, and cream.

Table 2 shows examples of representative classifications and ingredients of various cosmetic ingredients. Additionally, cosmetic ingredients listed in the Quasi-drug Ingredients Standards 2006 (published by Yakuji Nipposha Co., Ltd., June 16, 2006) and the International Cosmetic Ingredient Dictionary and Handbook (published by The Cosmetic, Toiletry, and Fragrance Association, Eleventh Edition 2006) may also be blended.

Examples of the present invention are described below in detail.

[Example 1]
300 g of porphyran powder (manufactured by MMO) was suspended in 5700 g of pure water. 30 g of protease (Flavorzyme 1000 L, manufactured by Novozymes) was added to the suspension and stirred at 25°C for 19 hours. The suspension was filtered through a quantitative filter paper (Advantec Toyo Co., Ltd. No. 2) using a Buchner funnel (3.2 L, manufactured by Sekiya Rika Glass Instruments Co., Ltd.). The filtrate was then repeatedly washed with pure water until the conductivity of the filtrate reached 1 mS/m or less to remove the protease. The cake-like substance obtained by this protein removal treatment was dried at 60°C for 12 hours. 250 g of porphyran powder with a protein content reduced to 87 ppm was obtained.

Next, 150 g of this porphyran powder was suspended in 2,850 g of pure water. This suspension was passed through a column packed with 200 mL of cation exchange resin (SK1BH, manufactured by Mitsubishi Chemical Corporation) to reduce arsenic. 300 g of the resulting porphyran suspension was taken, heated to 80°C, and held for 30 minutes. Subsequently, ultrasonic irradiation was performed for 3 minutes at 100% ultrasonic output using a horn-type ultrasonic disperser (SONOPLUS HD2070, manufactured by BANDELIN). The mixture was then cooled to 23°C, and the pH was adjusted to 9.1 by adding a 1% aqueous _NH3 solution. This resulted in a porphyran dispersion with a solids concentration of 5%.

This Porphyran dispersion was spray-dried to obtain a powder of Porphyran particles. In this example, the dispersion was supplied at a rate of 1 liter/minute into a hot air stream with an inlet temperature of 160°C. Spraying was performed using an atomizer, with the rotation speed set to 27,000 rpm. In this example, the outlet temperature was measured to be 55°C. An SEM photograph of the resulting Porphyran particles is shown in Figure 1.

The spraying conditions for the Porphyran particles are shown in Table 3. The physical properties of the Porphyran particle powder were measured using the following method. The results are shown in Table 4. The same applies to the Examples and Comparative Examples described below.

(1) Average Particle Diameter The particle size distribution of the Porphyran particles was measured by laser diffraction. Here, the particle size distribution was measured using an LA-950v2 manufactured by Horiba, Ltd. The median value was calculated from the obtained particle size distribution and used as the average particle size.

(2) Sphericity Photographs were taken at magnifications of 2,000 to 250,000 times using a transmission electron microscope (Hitachi, H-8000) to obtain a photographic projection. From the photographic projection, 50 particles were randomly selected, and their maximum diameters D _L and their minor diameters D S perpendicular to the maximum diameters D _L were measured, and the ratio (D _S /D _L ) was calculated. The average value of these values was taken as the sphericity.

(3) Arsenic Content Approximately 1 g of porphyran particle powder was placed on a platinum dish, to which 5 ml of nitric acid and 10 ml of hydrofluoric acid were added, and the mixture was heated on a sand bath. After drying, a small amount of water and 50 ml of nitric acid were added to dissolve the mixture in a 100 ml measuring flask, and water was added to make a 100 ml solution. Five 10 ml aliquots were then obtained from this solution (100 ml). The arsenic content was then measured using an ICP plasma emission spectrometer (SII, SPS5520) by the standard addition method.

(4) Protein Content The protein content was determined by the Kjeldahl method. Specifically, the powder of porphyran particles was thermally decomposed with sulfuric acid, and the nitrogen in the sample was converted to ammonium sulfate. Next, the decomposition solution was made alkaline, and the liberated ammonia was distilled, and the amount of N was measured by titration. The protein content was determined by multiplying this amount of N by 6.25.

(5) Moisture Retention A porphyran powder was placed in a porcelain crucible from which adsorbed moisture had been removed in advance at 500°C for 1 hour, and exposed to conditions of 40°C and 90% RH for 12 hours. It was then dried at 105°C for 2 hours, and the weight loss was measured. The weight loss (wt%) was taken as the moisture retention of the porphyran particles.

[Example 2]
A powder of porphyran particles was obtained in the same manner as in Example 1, except that the rotation speed of the atomizer was set to 20,000 rpm.

[Example 3]
A two-fluid nozzle was used to spray the porphyran dispersion at a spray air pressure of 0.4 MPa. At this time, the porphyran dispersion was supplied at a rate of 2 liters/minute into a hot air stream with an inlet temperature of 190° C. A powder of porphyran particles was obtained in the same manner as in Example 1.

[Example 4]
The spray air pressure was set to 0.5 MPa, and the Porphyran dispersion was supplied at a rate of 1 liter/minute into a hot air stream having an inlet temperature of 160° C. Except for this, a powder of Porphyran particles was obtained in the same manner as in Example 3.

[Comparative Example 1]
A powder of porphyran particles was obtained in the same manner as in Example 1, except that the rotation speed of the atomizer was set to 5,000 rpm.

[Comparative Example 2]
In this comparative example, a powder of Porphyran particles was obtained in the same manner as in Example 1, except that the protein reduction treatment was not performed. That is, 150 g of Porphyran powder (manufactured by MMO) was suspended in 2,850 g of pure water, and the arsenic reduction treatment was performed. Thereafter, a powder of Porphyran particles was prepared in the same manner as in Example 1.

<Tactile properties of Porphyran particle powder>
Next, the tactile properties of the powders obtained in each Example and Comparative Example were evaluated. A sensory test was conducted for each powder by 20 expert panelists, who interviewed them regarding seven evaluation items: smooth feel, moist feel, rolling feel, uniform spreadability, adhesion to the skin, duration of rolling feel, and soft feel. The evaluation scores of each panelist based on evaluation criteria (a) were totaled, and the tactile properties were evaluated based on evaluation criteria (b). The results are shown in Table 5.
Evaluation criteria (a)
5 points: Very good.
4 points: Excellent.
3 points: Average.
2 points: Inferior.
1 point: Very poor.
Evaluation Criteria (b)
◎: Total score is 80 points or more ○: Total score is 60 points or more but less than 80 points △: Total score is 40 points or more but less than 60 points ▲: Total score is 20 points or more but less than 40 points ×: Total score is less than 20 points

<Usage of powder foundation>
Powder foundations were prepared using the Porphyran particle powder in the blending ratios (wt %) shown in Table 6. Specifically, the powder obtained in each example was used as component (1), and was placed in a mixer along with components (2) to (9) and stirred to achieve a uniform mixture. Next, cosmetic components (10) to (12) were added to the mixer and stirred to achieve a further uniform mixture. The resulting cake-like substance was crushed, and approximately 12 g of the substance was removed and placed in a 46 mm x 54 mm x 4 mm metal dish for press molding. The powder foundations thus obtained were subjected to a sensory test by 20 expert panelists. Interviews were conducted regarding six evaluation criteria: uniform spread, moist feeling, and smoothness during application to the skin, and the uniformity, moist feeling, and softness of the cosmetic film after application to the skin. The scores of each panelist based on the aforementioned evaluation criteria (a) were totaled, and the feel of the foundation upon use was evaluated based on the aforementioned evaluation criteria (b). The results are shown in Table 7.

Claims (6)

Porphyran particles formed by the aggregation of porphyran, a trans-type polysaccharide composed of galactose molecules, characterized by an average particle size of 0.5 to less than 20 μm and a protein content of less than 100 ppm. The porphyran particles according to claim 1, having a sphericity of 0.85 or more. The porphyran particles according to claim 1 or 2, having an arsenic content of less than 5 ppm. The Porphyran particles according to any one of claims 1 to 3, which retain moisture at a rate of 30% or more when left at 40°C/90% RH for 12 hours. The porphyran particles according to any one of claims 1 to 4, wherein the porphyran content in the porphyran particles is 90% or more. A cosmetic preparation containing the Porphyran particles according to any one of claims 1 to 5.