JP6913456B2 - Caffeine adsorbent and caffeine adsorption method - Google Patents

Description

The present invention relates to a caffeine adsorbent and a caffeine adsorbing method.

Caffeine is represented by the following structural formula, and is contained in coffee beans, tea leaves, mate tea leaves, cola fruits, etc. in the natural world. Caffeine has actions such as excitement of the central nervous system, cardiotonic and diuretic, and from the viewpoint of health consciousness, in recent years, caffeine-less beverages such as tea, coffee, black tea, and energy drinks excluding caffeine have been introduced. Demand is rising.

As an adsorbent for removing caffeine from beverages, clays and zeolites containing montmorillonite as a main component such as acid clay and activated clay (acid-treated product of acid clay) are known (Patent Documents 1 to 3). ..

However, zeolite is not used industrially because it has poor selectivity for caffeine and adsorbs even the active ingredient contained in the beverage.

Montmorillonite has the advantages of high selective adsorption to caffeine, clay mineral, and low cost, but has the disadvantage that metal ions such as Al ion, Ca ion, and Fe ion are eluted in the beverage. There is. The amount of elution is not so large, but it causes the flavor of the beverage to be impaired. Therefore, it is required to suppress the elution of these metal ions.

By the way, magnesium silicate is known as a general adsorbent. However, in Japan at present, magnesium silicate is not permitted to be used as a food additive except when it is used as a filtration aid for fats and oils.

Japanese Patent Application Laid-Open No. 6-142405 Japanese Unexamined Patent Publication No. 2014-212742 JP 2015-163049

Therefore, an object of the present invention is a caffeine adsorbent which has high selective adsorption property to caffeine, effectively avoids elution of metal ions such as Al ions, and can be used for foods such as beverages. Is to provide.

Another object of the present invention is to provide a caffeine adsorption method that can effectively adsorb caffeine, do not elute metal ions, and can be applied to foods such as beverages.

According to the present invention, it is composed of silica-magnesia composite particles in which silica particles and magnesia particles are integrally composited, and the anion adsorption capacity represented by the amount of Orange II adsorbed is in the range of 18 to 74 mmol / 100 g. A caffeine adsorbent is provided.
In the present invention, the anion adsorption capacity is measured using a 10 mmol / L orange II aqueous solution.

In the caffeine adsorbent of the present invention, the silica component and the magnesia component are expressed by the following formula:
R = Sm / Mm
In the formula, Sm is the content (mass%) of the silica component in terms of _{SiO 2.}
Mm is the content (mass%) of the magnesia component in terms of MgO.
It is preferable that the mass ratio (R) represented by is 0.1 ≦ R ≦ 3.5.

Further, according to the present invention, there is also provided a caffeine adsorption method, which comprises adding the adsorbent to a caffeine-containing aqueous solution to adsorb caffeine.

In the caffeine adsorption method of the present invention,
(1) The caffeine concentration in the caffeine-containing aqueous solution is 0.001 to 1.0% by mass.
(2) It is preferable to add 0.001 to 25 parts by mass of the adsorbent per 100 parts by mass of the caffeine-containing aqueous solution.

The caffeine adsorbent of the present invention comprises silica particles and magnesia particles. Since neither the silica particles nor the magnesia particles have metal ions such as Al ions, Ca ions, and Fe ions that cause damage to the flavor of the beverage, the adsorbent of the present invention composed of such particles is also a metal of these. It has no ions and therefore effectively avoids elution of these metal ions.

Further, as described above, magnesium silicate cannot be used as a food additive except when it is used as a filtration aid for fats and oils, but the adsorbent of the present invention is a silica component approved as a food additive. It is a silica magnesia that is an integral composite of magnesia components. Therefore, the caffeine adsorbent of the present invention can be applied to foods such as beverages.

The caffeine adsorbent of the present invention exhibits high selective adsorption to caffeine due to the structural feature that silica particles and magnesia particles are integrally composited, and examples thereof will be described later. As shown by, its caffeine adsorption property is equal to or higher than that of acid clay.

Therefore, the caffeine adsorbent of the present invention can be used when removing caffeine from foods such as beverages, and is particularly suitable for the production of caffeine-less beverages.

The caffeine adsorbent of the present invention comprises silica-magnesia composite particles. Silica-magnesia composite particles are substantially formed of silica components and magnesia components that are approved as adsorbents and filtration aids for food production, and are raw materials such as silica (silicon dioxide) particles and magnesia (oxidation). Magnesium) particles are dispersed and homogeneously mixed as nano-order unit particles (nanoparticles) in water, although they are not dissolved, and maintain high adsorption ability to anionic dye (Orange II) derived from magnesia component. It is a particle that is tightly integrated as it is.

[Integral composite and structure in silica-magnesia composite particles]
In the present invention, silica (A) and magnesia or its hydrate (B) are homogeneously mixed in the presence of water to form an aqueous slurry (homogeneous mixing), and then aged to further remove water. As a result, the desired silica-magnesia composite particles can be obtained.

That is, in the presence of water, for example, by homogeneous mixing in water, silica (silicon dioxide), which is one of the raw materials, is dissolved into colloidal particles to fine agglomerated particles (primary to secondary particles). The other magnesia (magnesium oxide) also hardly dissolves when it is put into water and stirred or crushed, but its crystals (or newly formed hydrate) are formed by partial hydration of the surface of magnesia particles. Part or all of the crystals) are disintegrated or exfoliated to form fine particles composed of magnesia (magnesium oxide) and / or magnesium oxide hydrate and dispersed in water.

In the aging step, when water is removed from the slurry in which these fine particles are uniformly dispersed and the solid content concentration increases, the silica particles (A) and the magnesia particles (B) gradually or rapidly become the same. They approach each other and reach an integrally composited form without chemical bonds that involve atom exchange or recombination (completion of integral complexation). That is, the silica-magnesia composite particles of the present invention have an integrated structure so as not to be separated by physical means.

In the present invention, because the silica component and the magnesia component are integrally composited as described above, the adsorption ability to the anionic dye (Orange II) derived from the magnesia component is maintained high, and the adsorption amount of Orange II is maintained. The anion adsorption capacity represented by is in the range of 18 to 74 mmol / 100 g, and excellent caffeine adsorption property is acquired. For example, when a silica component and a magnesia component form a chemical bond, such as magnesium silicate, the anion adsorption capacity represented by the amount of Orange II adsorbed is as low as 17 or less, and the caffeine adsorption property is extremely low. (See Comparative Example 1).

In addition, the caffeine adsorption properties of silica alone and magnesia alone are also extremely low (see Comparative Examples 2 to 4). Therefore, it is inevitable that the caffeine adsorption property of the mixture obtained by simply dry mixing silica and magnesia is also low.

As described above, when the silica component or the magnesia component exists alone or in the state of a reactant, caffeine can hardly be adsorbed, but it is extremely surprising that these components can be used as in the present invention. High caffeine selective adsorption can be obtained by integrally compounding so that the adsorption ability to the anionic dye (Orange II) derived from the magnesia component is maintained high.

In the present invention, the mass ratio of the silica component and the magnesia component may be appropriately determined, but from the viewpoint of the degree of integral composite, the mass ratio (R) represented by the following formula is 0.1 ≦ R ≦ 3. 5, particularly preferably 1.3 ≦ R ≦ 3.0, and further preferably 1.5 ≦ R <2.5.
R = Sm / Mm
In the formula, Sm is the content (mass%) of the silica component in terms of _{SiO 2.}
Mm is the content (mass%) of the magnesia component in terms of MgO.

The degree of integral compounding depends on the mass ratio (R) of the silica component and the magnesia component in the adsorbent. For example, when the mass ratio is around 2 (R≈2, preferably 1.5≤R <2.5), the silica component and the magnesia component have a mass ratio that is just right for the integral composite, and will be described in Examples described later. As shown above, the anion adsorption capacity represented by the amount of Orange II adsorbed is as high as 18 mmol / 100 g or more, and the degree of integral compounding is very high.

As the mass ratio becomes less than 2 (R <2) and the region becomes relatively magnesia-rich, a large number of magnesia fine particles form an entire magnesia matrix phase, and the particles are diluted in the magnesia matrix phase. It is considered that the silica component is dispersed, that is, the degree of integral composite is considered to be low. Further, when the magnesia component becomes rich and R <0.1, the anion adsorption ability represented by the amount of Orange II adsorbed by the silica-magnesia composite particles of the present invention falls out of the above range, and as a result, caffeine Not only is there a risk that the adsorptive capacity will decline, but the magnesia component will be unnecessarily hydrated by the moisture in the air over time, and the anion adsorptive capacity cannot be maintained within the above range over a long storage period. There is. In particular, the hydration of the magnesia component over time greatly affects the adsorptive ability of the anionic dye (Orange II) derived from the magnesia component. Therefore, if the mass ratio (R) does not satisfy the above range, the anion adsorption capacity is lowered due to the influence of hydration, and as a result, a high caffeine adsorption capacity cannot be maintained. In the present invention, the silica component effectively suppresses the hydration of the magnesia component, and as a result, exhibits high caffeine adsorption capacity.

On the contrary, as the mass ratio exceeds 2 (2 <R) and the region becomes relatively silica-rich, a large number of silica fine particles form an amorphous silica matrix phase throughout. , It is considered that the magnesia component is dilutedly dispersed in it, that is, the degree of integral compounding is also considered to be low. In particular, when the silica component is large and 3.5 <R, the silica component is excessive and the adsorption ability to the anionic dye (Orange II) derived from the magnesia component is lowered, so that the silica of the present invention is used. -The anion adsorption capacity represented by the amount of Orange II adsorbed by the magnesia composite particles may be out of the above range, and as a result, the caffeine adsorption capacity is lowered.

Since the silica-magnesia composite particles of the present invention are integrally composited so as to maintain high adsorption ability to the anionic dye (Orange II) derived from the magnesia component, the anion represented by the amount of Orange II adsorbed. The adsorption capacity is 18 mmol / 100 g or more, and from the viewpoint of caffeine adsorption capacity, it is preferably 20 mmol / 100 g or more. Further, it is 74 mmol / 100 g or less, preferably 71 mmol / 100 g or less from the viewpoint of integral composite.

[Preferable characteristics]
As described above, in the caffeine adsorbent of the present invention composed of silica-magnesia composite particles, the silica component and the magnesia component are maintained at a high adsorption ability to the anionic dye (orange II) derived from the magnesia component. It is integrally composited, and preferably contains a silica component and a magnesia component in a constant amount ratio. Thereby, in the present invention, the amount of caffeine adsorbed per 1 g of the dried adsorbent is 39 mg or more, particularly 45 mg or more, which can be suitably used for removing caffeine contained in beverages and the like, and can be used to produce caffeine-less beverages. Is extremely advantageous.

In silica-magnesia composite particles, the pH of the suspension is usually in the range of 6.0 to 10.0 because the silica component and the magnesia component are not liberated from each other and are closely compounded.

The BET specific surface area measured by the nitrogen adsorption method is preferably 100 m ² / g or more, ^{more preferably 500 m 2} / g or more, and particularly preferably 600 m ² / g or more, in that caffeine can be stably adsorbed.

[Preferable dosage form]
The caffeine adsorbent of the present invention is preferably a powder having a particle content of less than 5 μm of 20% by volume or less, further 12% by volume or less, particularly 10% by volume or less. As a result, more stable and uniform adsorption processing can be performed.

Further, instead of using the powder having the particle size distribution as described above, from the viewpoint of improving the filterability and the like, a spherical or elliptical spherical shape having a diameter or major axis of 5 μm to 5 mm, or a spherical or elliptical spherical shape having a diameter of 0.5 mm or more and a shaft length of 0.5 mm or more. Cylindrical particles of 50 mm or less can also be used.

Such silica-magnesia composite particles are commercially available, for example, from Mizusawa Industrial Chemicals Co., Ltd. under the trade name of "Mizuka Life".

[Manufacturing method of silica-magnesia composite particles]
In order to produce the above-mentioned caffeine adsorbent of the present invention, (A) silicon dioxide (silica) and (B) magnesium oxide (magnesia) or a hydrate thereof are used as raw materials. All of these are approved as filtration aids or adsorbents for food production, and therefore their use does not limit their use as food purification.

Further, as the silica (A) and magnesia or its hydrate (B), it is preferable to select those that can be easily made into nanoparticles, which will be described later.
For example, the silica is preferably an amorphous water-containing type and may be produced by either a gel method or a sedimentation method, but a silica having a small primary particle is preferable and has a specific surface area. Those having a capacity of 40 m ² / g or more, particularly 140 m ² / g or more, are preferable.
Further, as the magnesia or its hydrate, those having small crystallites and not being carbonated with time are preferable. For example, magnesia powder having a specific surface area of 2 m ² / g or more, preferably 20 m ² / g or more, particularly preferably 50 m ² / g or more is used.

As described above, the silica (A) and magnesia or its hydrate (B) have a mass ratio R (Sm / Mm) of the silica component and the magnesia component in the caffeine adsorbent, which is the target substance, of 0.1. It is used at a ratio of ≦ R ≦ 3.5, particularly 1.3 ≦ R ≦ 3.0, and further 1.5 ≦ R <2.5. By using in such an amount ratio, excellent caffeine adsorption can be ensured.

In the preparation of the aqueous slurry, there are no restrictions on the order of adding each of the raw materials (A) and (B) and water, but when aggregation or gelation phenomenon (thickening) occurs, the above-mentioned fine particle formation (nanoparticle formation) occurs. And there is a risk that the progress of integral compounding will be hindered. Therefore, it is preferable that the solid content concentration of the aqueous slurry is low. On the other hand, from the viewpoint of productivity and economy, the higher the solid content concentration is, the better. Therefore, the solid content concentration is preferably 3 to 15% by mass, particularly preferably 8 to 13% by mass.

Further, gelation is likely to occur by heating, but the above-mentioned homogeneous mixing and aging are preferably carried out at 100 ° C. or lower, preferably at 50 to 97 ° C., and particularly preferably at 50 to 79 ° C.

The preparation and aging of the aqueous slurry by homogeneous mixing of the raw materials (A) and (B) is generally carried out under stirring in a stirring tank equipped with a stirring blade, but is pulverized or dispersed by a wet ball mill or a colloid mill. You can also do it below.
Aging is a step for sufficiently performing the above-mentioned nanoparticulation (fine particle formation) and integral compounding, and homogeneous mixing and aging for the preparation of an aqueous slurry differ depending on the temperature, the charging capacity of the slurry, and the like. However, at least 0.5 hours is required. Further, the higher the temperature, the higher the fluidity of the nanoparticles and the more efficiently the nanoparticles are homogenized, so that the process can be performed in a shorter time. Generally, mixing and aging are carried out over 1 to 24 hours, particularly about 3 to 10 hours.

Moisture removal after aging is performed by evaporation drying using a spray dryer, slurry dryer, etc., but after performing some dehydration by means such as filtration or centrifugation, a box dryer, band dryer, etc. , You may perform drying using a fluidized layer dryer or the like. At this time, at least a part or all of the hydration of the raw material (B) is eliminated.

As described above, for example, the water content is 10% by mass or less, and the silicon dioxide (silica) particles and the magnesia particles, which are the raw material particles, are closely compounded by dehydration, and at least a part of the silica particles and the magnesia particles are formed. The integrally composited silica-magnesia composite particles can be obtained in the form of granules, powder, cake or baby boom. These are crushed, classified, or molded as necessary, and are suitably used for adsorbing and removing caffeine from, for example, beverages in a desired particle shape.

The above pulverization can be performed by a dry pulverization method known per se, for example, an impact pulverizer such as an atomizer, a dry ball mill, a roller mill, a jet mill, or the like.
Further, the classification is performed by gravity classification, centrifugal classification, inertial classification, etc. using a normal dry classifier.
By such pulverization and classification, the adsorbent of the present invention can be obtained, for example, in the form of a powder having a fine particle content of less than 5 μm of 20% by volume or less.

Further, the molding can be performed by any method such as rolling granulation, fluidized bed granulation, stirring granulation, crushing granulation, compression granulation, extrusion granulation, etc., but in general, the granules are granulated. It should be molded so as to have a strength that does not become too hard and does not easily powder. By such molding, for example, the adsorbent of the present invention is in the form of spherical or elliptical spherical particles having a diameter or major axis of 5 μm to 5 mm, or cylindrical particles having a diameter of 0.5 mm or more and an axial length of 50 mm or less. Is obtained.

The adsorbent of the present invention thus obtained is suitably used for removing caffeine from a caffeine-containing aqueous solution such as a caffeine-containing beverage. Specifically, caffeine can be adsorbed by making the adsorbent of the present invention into a powder having an appropriate size and shape as needed and adding it to a caffeine-containing aqueous solution.

The caffeine concentration in the caffeine-containing aqueous solution is not particularly limited, but is usually 0.001 to 1.0% by mass.

The amount of the adsorbent of the present invention to be added is also not particularly limited, but it is generally preferable to use 0.001 to 25 parts by mass per 100 parts by mass of the caffeine-containing aqueous solution.

The adsorbent of the present invention adsorbing caffeine is separated and taken out by a known method such as centrifugation or filtration. As a separation method, filtration is preferable from the viewpoint of less loss of the active ingredient.

The excellent effect of the present invention will be described with reference to the following experimental examples.

(1) BET Specific Surface Area by Nitrogen Adsorption Method Measurement was performed by the nitrogen adsorption method using TriStar 3000 manufactured by Micromeritics, and the measurement was performed by the BET method. The pretreatment was carried out at 150 ° C. for 2 hours.

(2) Caffeine Adsorption Test The caffeine adsorption capacity in this example is the amount of caffeine (mg) capable of adsorbing 1 g of an adsorbent (anhydrous) from a 0.2 g / L concentration caffeine aqueous solution, and the following method. Was measured and calculated.
First, anhydrous caffeine (special grade reagent, manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved in ion-exchanged water to obtain a 0.2 g / L concentration caffeine aqueous solution.
30 g of this 0.2 g / L concentration caffeine aqueous solution is weighed in a 50 ml volume centrifuge tube, 0.1 g of an adsorbent (0.33% by mass with respect to the liquid) is added, and a shaker (manufactured by Yamato Scientific Co., Ltd.) It was shaken for 2.5 hours by SA300 and shaking speed 5).
Next, the supernatant of the liquid treated with a centrifuge (5200 manufactured by Kubota Co., Ltd.) at a centrifugal acceleration of 3000 rpm for 20 minutes was diluted 10-fold with ion-exchanged water to obtain a liquid (sample liquid). The absorbance of the 273 nm wavelength light of the sample solution was measured with a spectrophotometer (V-630 manufactured by JASCO Corporation). Then, the residual amount of caffeine in the sample solution was calculated using a calibration curve showing the relationship between the caffeine concentration prepared in advance and the absorbance of 273 nm wavelength light, and the value subtracted from the amount of caffeine before the addition of the adsorbent was subtracted from the adsorbent. The amount of caffeine adsorbed was used.

(3) Orange II Adsorption Amount The Orange II adsorption capacity in this example was calculated by measuring and calculating the number of mmol of Orange II capable of adsorbing 1 g of a sample from an aqueous solution of Orange II having a concentration of 10 mmol / L.
First, Orange II (special grade reagent, manufactured by Wako Pure Chemical Industries, Ltd.) is dissolved in water to obtain an orange II aqueous solution having a concentration of 10 mmol / L. Weigh 20 ml of this 10 mmol / L concentration Orange II aqueous solution into a 50 ml centrifuge tube, add 0.20 g of test powder, and use a shaker (SA300 manufactured by Yamato Scientific Co., Ltd., shaking speed 5) to 7.5. Shake the time. After shaking, let stand for 12 hours or more. Next, 0.5 mL of the supernatant of the solution treated with a centrifuge (5200 manufactured by Kubota Corporation) at a centrifugal acceleration of 3000 rpm for 15 minutes was collected, and this was diluted 200-fold with ion-exchanged water to obtain the absorbance of 484 nm wavelength light. Was measured with a spectrophotometer (V-630 manufactured by JASCO Corporation). Then, the residual amount of Orange II in the sample solution was calculated using a calibration curve showing the relationship between the Orange II content of the Orange II aqueous solution and the absorbance of 484 nm wavelength light. The value obtained by subtracting this value from the amount of Orange II added to the sample is taken as the amount of Orange II adsorbed.

Table 1 shows the physical characteristics and the results of the caffeine adsorption test for the adsorbent powders shown in the following Examples and Comparative Examples.

(Example 1)
Silica magnesia preparation manufactured by Mizusawa Industrial Chemicals Co., Ltd. Mizuka Life F-1G was used as silica-magnesia composite particles.

(Example 2)
Silica magnesia preparation manufactured by Mizusawa Industrial Chemicals Co., Ltd. Mizuka Life F-2G was used as silica-magnesia composite particles.

(Comparative Example 1)
Magnesium MAGNESOL XL manufactured by Dallas was used.

(Comparative Example 2)
Silicon dioxide Mizuka Sorb C-1 manufactured by Mizusawa Industrial Chemicals Co., Ltd. was used.

(Comparative Example 3)
Lightly baked magnesium oxide Starmag U manufactured by Konoshima Chemical Co., Ltd. was used.

(Comparative Example 4)
Lightly baked magnesium oxide Starmag P manufactured by Konoshima Chemical Co., Ltd. was used.

(Comparative Example 5)
Mizusawa Industrial Chemicals Co., Ltd. Acid clay Mizuka Ace No. 20 was used.

Claims (4)

It is composed of silica-magnesia composite particles in which silica particles and magnesia particles are integrally composited, and the anion adsorption capacity represented by the amount of Orange II adsorbed is in the range of 18 to 74 mmol / 100 g .
The silica component and the magnesia component are expressed by the following formula:
R = Sm / Mm
In the formula, Sm is the content (mass%) of the silica component in terms of _{SiO 2.}
Mm is the content (mass%) of the magnesia component in terms of MgO.
A caffeine adsorbent contained in a mass ratio (R) represented by the above in a ratio of 0.1 ≦ R <3.5.
A caffeine adsorbent characterized in that the amount of caffeine adsorbed per 1 g of the dried caffeine adsorbent is 39 mg or more. A method for adsorbing caffeine, which comprises adding the adsorbent according to claim 1 to an aqueous solution containing caffeine to adsorb caffeine. The caffeine adsorption method according to claim 2 , wherein the caffeine concentration in the caffeine-containing aqueous solution is 0.001 to 1.0% by mass. The caffeine adsorption method according to claim 2 or 3 , wherein the adsorbent is added in an amount of 0.001 to 25 parts by mass per 100 parts by mass of the caffeine-containing aqueous solution.