JP2009091180A - Calcium carbonate having high rate of biologic absorption and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide calcium carbonate having a high in a biological absorption rate of calcium and a method for producing the same. <P>SOLUTION: The calcium carbonate is obtained through a first carbonation step of blowing CO<SB>2</SB>gas-containing gas having a CO<SB>2</SB>gas concentration of ≥15 vol.% into an aqueous calcium hydroxide suspension having a solid content of 5-10 wt.% and a temperature of 15-20°C at a rate of ≥25 l/min per 1 kg of calcium hydroxide to allow a carbonation reaction to proceed up to a rate of carbonation of ≥90%; a final carbonation step of adding an aqueous suspension prepared such that calcium hydroxide is contained in an amount of 5-20 parts based on 100 parts of solid calcium hydroxide used for feed at the first carbonation step to the suspension after the first carbonation step, and blowing CO<SB>2</SB>gas-containing gas having a CO<SB>2</SB>gas concentration of ≥10 vol.% at a rate of ≥15 l/min per 1 kg of calcium hydroxide to allow a carbonation reaction to proceed up to pH 6.6-7.5 and a rate of carbonation of ≥95%; and a step of drying the resulting aqueous calcium carbonate suspension after the final carbonation step in a state with a solid content of ≤60%. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to calcium carbonate having a high bioabsorption rate and a method for producing the same.

  Calcium is contained in the human body in about 2.0% of body weight, and most of it is present in bones and teeth as calcium phosphate and constitutes the human body. Calcium, together with phosphorus and magnesium, is closely related to nerve transmission, muscle contraction, cell membrane permeability, etc., and if it is chronically deficient, physiological activities in the body cannot be performed smoothly. Therefore, as one of the important minerals, calcium is examined in Japan in the third revised “Nutrition Requirements for Japanese People” (Ministry of Health and Welfare, 1984). Since then, the trend toward emphasis on calcium has not changed from 2005 to the “2005 Japanese Dietary Intake Standards”.

  Calcium is abundant in foods such as small fish, milk, and Japanese mustard spinach, but many processed foods with enhanced calcium content are now on the market. There are various types such as soft drinks, confectionery (biscuits, snacks, tablet confectionery, gum, etc.), instant noodles, kneaded products, milk drinks, yogurt and the like. It is also added to infant formula, liquid foods for the sick, etc. due to the need for supplementation.

  Conventionally, designated additives such as calcium lactate, calcium carbonate, and calcium phosphate, existing additives such as unfired shell shell calcium, or food materials such as whey calcium are used for calcium strengthening of foods. Calcium carbonate is often used for reasons such as excellent storage stability.

Calcium carbonate is produced by calcining limestone into quick lime, blowing carbon dioxide into lime milk that has been reacted with water, obtaining calcium carbonate crystals, and then dehydrating, drying, and gasifying the powder There are a legal method (see, for example, Patent Document 1), a pulverization method obtained by finely pulverizing and classifying high-purity limestone, a method of reacting hydrated slaked lime with sodium carbonate, and the like.
Japanese Patent No. 2881555

  Calcium carbonate produces powders with different physical properties such as particle shape, specific surface area, bulk specific gravity, etc., depending on the production method and reaction conditions. Conventionally, even if these physical properties are different, there is no difference in digestion and absorption, and nutrition. Was thought to be similar.

  The present invention has been made because knowledge different from the conventional idea has been obtained, and an object of the present invention is to provide calcium carbonate having a high bioabsorption rate of calcium and a method for producing the same.

  In the calcium carbonate according to the present invention, a carbon dioxide-containing gas having a carbon dioxide concentration of 15% by volume or more is added to a calcium hydroxide aqueous suspension having a solid content of 5 to 10 wt% and a temperature of 15 to 20 ° C. Used in the first carbonation step in the first carbonation step in which the carbonation reaction was carried out to a carbonation rate of 90% or more, and the suspension after completion of the first carbonation step. A water suspension prepared to contain 5 to 20 parts of calcium hydroxide is added to 100 parts of calcium hydroxide solid content, and a carbon dioxide-containing gas having a carbon dioxide concentration of 10% by volume or more is added to 15 parts per 1 kg of calcium hydroxide. The final carbonation step in which carbonation reaction is performed until the pH of the suspension is 6.5 to 7.5 and the carbonation rate is 95% or more, and calcium carbonate after the final carbonation step. water The turbid liquid is obtained by passing through a step of drying in a state where the solid content is 60% or less. This calcium carbonate has a bioabsorption rate of calcium of 10% or more based on a calcium balance test by rats. It is.

  The calcium carbonate aqueous suspension after the final carbonation step is preferably subjected to the drying step after being subjected to a dehydration step in which the solid content is in a range of 30 to 60%. Moreover, it prepared so that 5-20 parts of calcium hydroxide might be contained in the suspension after completion | finish of said 1st carbonation process with respect to 100 parts of calcium hydroxide solid content used for preparation of the 1st carbonation process. A second carbonic acid is added by adding a water suspension and blowing a carbon dioxide-containing gas having a carbon dioxide concentration of 10% by volume or more at a rate of 15 liters / minute or more per 1 kg of calcium hydroxide to carry out a carbonation reaction to a carbonation rate of 70 to 95%. It is preferable to perform the final carbonation step after repeating the carbonization step one or more times.

  The method for producing calcium carbonate according to the present invention comprises a calcium hydroxide aqueous suspension having a solid content of 5 to 10 wt% and a temperature of 15 to 20 ° C., and a carbon dioxide containing gas having a carbon dioxide concentration of 15% by volume or more. Blowing at a rate of 25 liters / minute or more per kg and conducting a carbonation reaction to a carbonation rate of 90% or more, and charging the first carbonation step into the suspension after the completion of the first carbonation step A water suspension prepared so as to contain 5 to 20 parts of calcium hydroxide is added to 100 parts of calcium hydroxide solid content used in the above, and a carbon dioxide-containing gas having a carbon dioxide concentration of 10% by volume or more is added to calcium hydroxide. A final carbonation step in which carbonation is carried out until the pH of the suspension is 6.5 to 7.5 and the carbonation rate is 95% or more, and after the final carbonation step. Carbonated mosquito The Siumu aqueous suspension, in the solid component following 60% state, and a step of drying.

  The method for producing calcium carbonate according to the present invention preferably further includes a dehydration step of dehydrating the calcium carbonate aqueous suspension after the final carbonation step so that its solid content is in the range of 30 to 60%. In that case, in the drying step, the calcium carbonate aqueous suspension after the dehydration step is dried. Moreover, the manufacturing method of the calcium carbonate which concerns on this invention is 5-5 with respect to 100 parts of calcium hydroxide solid content used for preparation of the 1st carbonation process in the suspension after the said 1st carbonation process completion | finish. A water suspension prepared to contain 20 parts of calcium hydroxide was added, and a carbon dioxide-containing gas having a carbon dioxide concentration of 10% by volume or more was blown at a rate of 15 liters / minute or more per 1 kg of calcium hydroxide, and the carbonation rate was 70 to It is preferable to further include a second carbonation step in which the carbonation reaction is performed up to 95%. In this case, after the second carbonation step is repeated one or more times, the final carbonation step is performed.

  ADVANTAGE OF THE INVENTION According to this invention, the calcium carbonate with the high bioabsorption rate of calcium and its manufacturing method can be provided.

  Hereinafter, an embodiment of a method for producing calcium carbonate according to the present invention will be described. The method for producing calcium carbonate according to the present invention is based on a gas compounding method, and is a further improvement of the method described in Japanese Patent No. 2881555. In the present embodiment, a first carbonation step, a second carbonation step, a final carbonation step, a dehydration step, and a drying step are performed.

  In the first carbonation step, a carbon dioxide-containing gas having a carbon dioxide concentration of 15% by volume or more is added to a calcium hydroxide aqueous suspension having a solid content of 5 to 10 wt% and a temperature of 15 to 20 ° C. The carbonation reaction is performed until the carbonation rate reaches 90% or more.

  When the concentration of the calcium hydroxide aqueous suspension is less than 5 wt%, there is a possibility that irregular shaped particles of calcium carbonate are generated. On the other hand, when it exceeds 10 wt%, coarse particles tend to be generated. When the temperature of the water suspension is less than 15 ° C., irregular shaped particles may be generated. On the other hand, when it exceeds 20 ° C., coarse particles tend to be generated.

  The upper limit of the carbon dioxide gas concentration of the carbon dioxide-containing gas depends on the reaction conditions and the like, but is preferably 40% by volume. The gas component other than carbon dioxide gas is not particularly limited as long as carbonation is not inhibited. For example, an inert gas such as nitrogen, air, or the like is preferable. When the flow rate of the carbon dioxide-containing gas is less than 25 liters / minute per 1 kg of calcium hydroxide, it is difficult to generate calcium carbonate chain particles, which is not preferable. Preferably it is 30 liters / minute or more. The upper limit of the flow rate depends on the reaction conditions and the like, but is preferably 200 liters / minute.

The carbonation rate is represented by the following formula.
Carbonation rate (%) = W / (W + W ₁ ) × 100
(W is the weight of calcium carbonate in the reaction solution and W ₁ is the weight of calcium hydroxide in the reaction solution.) When the carbonation rate in the first carbonation step is less than 90%, There is a problem in that the voids of the chain-like particles are clogged after the conversion step and dense crystals are formed. By setting the carbonation rate to 90% or more, desired porous particles can be obtained.

  In the second carbonation step, 5 to 20 parts of calcium hydroxide in the aqueous suspension after completion of the first carbonation step is 100 parts per 100 parts of calcium hydroxide solid content used in the first carbonation step. A calcium hydroxide aqueous suspension prepared to contain carbon dioxide is added, and a carbon dioxide containing gas having a carbon dioxide concentration of 10% by volume or more is blown at a rate of 15 liters / minute or more per 1 kg of calcium hydroxide, and the carbonation rate is 70 to 95%. Carbonation reaction is carried out until.

  After the second carbonation step, the temperature condition of the calcium hydroxide aqueous suspension to be added is not particularly limited. The aqueous suspension immediately after completion of the first carbonation step is usually about 30 to 50 ° C. due to the heat of reaction, and the temperature of the added aqueous suspension does not particularly affect the carbonation reaction.

  When the addition amount of the calcium hydroxide aqueous suspension is less than 5 parts by weight with respect to 100 parts by weight of the calcium hydroxide solid content in the first carbonation step, aggregates of chain particles are hardly generated. On the other hand, when the amount exceeds 20 parts by weight, as a result of newly generating calcium carbonate, aggregates of chain particles are hardly generated. The second carbonation step is preferably repeated once or more, more preferably 1 to 3 times.

  In the final carbonation step, a water suspension prepared to contain 5 to 20 parts of calcium hydroxide is added to 100 parts of calcium hydroxide solid content used in the preparation of the first carbonation step, and the concentration of carbon dioxide gas Carbon dioxide containing gas of 10% by volume or more is blown at a rate of 15 liters / minute or more per 1 kg of calcium hydroxide, and the carbonation reaction is carried out until the pH of the suspension is 6.5 to 7.5 and the carbonation rate is 95% or more. I do.

  The pH of the suspension, like the carbonation rate, is an index that represents the amount of calcium hydroxide remaining in the reaction. If a large amount of calcium hydroxide remains, recrystallization proceeds until the dehydration step, resulting in dense particles. Cannot be obtained and desired characteristics cannot be obtained. By carrying out the carbonation reaction until the pH of the suspension is 6.5 to 7.5 and the carbonation rate is 95% or more, desired porous particles can be obtained.

  The amount of calcium hydroxide added between the second carbonation step and the final carbonation step is cumulatively 20 parts or more with respect to 100 parts of calcium hydroxide solid content used for the preparation of the first carbonation step. It is preferable to do so. By setting such an input amount, desired porous particles can be obtained. The upper limit of the amount of calcium hydroxide added is preferably 30 parts and more preferably 35 parts.

  In the dehydration step, the calcium carbonate aqueous suspension after the final carbonation step is dehydrated so that the solid content remains in the range of 30 to 60% so as not to break the generated calcium carbonate particles. Porous calcium carbonate has a good reaction with acids such as stomach acid, and digestion and absorption are better than other calcium carbonates. However, even when porous calcium carbonate particles were generated in the carbonation step, the bioabsorption rate was greatly reduced when dehydration was performed so that the solid content was higher than 60% during the dehydration step. .

  This is presumed to be because if the dehydration rate is higher than the above value, the voids in the calcium carbonate particles are crushed during the dehydration step. On the other hand, if dehydration is stopped when the solid content is lower than 30%, drying after the dehydration process takes too much cost and time, which is not realistic. That is, the above range is the optimum dehydration rate for producing porous secondary particles of calcium carbonate. A more preferable dehydration rate is within a range of 30 to 40% solid content. As the dehydrator, a Niagara dehydrator or the like is preferably used.

  The dehydrated cake dehydrated to a predetermined solid content in the dehydration step is dried in the drying step. In addition, it is preferable to make it dry with a dryer after pre-drying for 24 hours or more in a normal temperature-80 degreeC dryer. As the dryer, it is preferable to use an air flow dryer such as a flash jet dryer or a tornesh dryer. The temperature at the outlet of the dryer is preferably 100 to 110 ° C. In addition, the water content of calcium carbonate is preferably 2% or less. In addition, when calcium carbonate powder becomes a lump after drying, it is preferable to crush this.

  The calcium carbonate according to the present invention manufactured by the above method has a bioabsorption rate of 10% or more based on the calcium balance test by rats, which is significantly higher than that by the conventional manufacturing method.

The calcium carbonate obtained by the method for producing calcium carbonate according to the present invention preferably has a porous shape mainly of calcite crystals and has the following physical properties.
-Bulk specific gravity: 1.0 g / mL or less.
-Purity: 98% or more.
-Lead content: 20 ppm or less.
-Average particle diameter: 0.05-15 micrometers.
-BET specific surface area: 6-50 m < ² > / g.
-Porosity: 0.5-2.5 mL / g.
-Oil absorption: 60-160 mL / 100g.
-Water absorption: 1.0-2.5 mL / g.

  Thus, since the calcium carbonate obtained by the manufacturing method of the calcium carbonate which concerns on this invention has a high bioabsorption rate, it is preferable to add to a foodstuff as a nutrient enhancement use. Examples of foods to which calcium carbonate according to the present invention is added include marine products, milk drinks, instant noodles, confectionery, bread, jelly, calcium tablet confectionery, nutritional supplements, and the like. The calcium carbonate according to the present invention is preferably added directly to these foods or added as a composition such as a food additive preparation.

  In the above embodiment, the first, second and final carbonation steps, the dehydration step and the drying step have been described. However, the present invention is limited to this embodiment. It is not a thing and other processes can be added, and a 2nd carbonation process and a spin-drying | dehydration process can be excluded.

  For example, the calcium carbonate aqueous suspension may be dried with a spray dryer without passing through the dehydration step after the final carbonation step. In this case, the calcium carbonate aqueous suspension usually has a solid content of 60% or less, and a calcium carbonate powder having a high bioabsorption rate can be obtained.

  Further, after the final carbonation step is completed, the calcium carbonate aqueous suspension may be wet pulverized with a dyno mill or the like, and then the dehydration step may be performed. By performing the pulverization step in this manner, calcium carbonate having predetermined powder properties can be stably obtained. Moreover, a grinding | pulverization process can also be performed after a drying process.

  Examples of the present invention will be described below. First, 500 kg of a calcium hydroxide aqueous suspension prepared at a concentration of 8 wt% and a temperature of 20 ° C. is placed in a reaction vessel, and carbon dioxide gas at a concentration of 30 vol% is blown into the reaction vessel at a flow rate of 40 liters / min per 1 kg of calcium hydroxide. Carbonation was carried out until the conversion rate reached 90% (first carbonation step).

  Next, 75 kg of aqueous calcium hydroxide suspension prepared at a concentration of 8 wt% and a temperature of 20 ° C. was added to the reaction vessel, and carbon dioxide gas at a concentration of 25 vol% was blown at a flow rate of 40 liters / min per 1 kg of calcium hydroxide. Carbonation was until 87% reached (second carbonation step).

  Furthermore, 75 kg of a calcium hydroxide aqueous suspension prepared at a concentration of 8 wt% and a temperature of 20 ° C. was added to the reaction vessel, and carbon dioxide gas of a concentration of 25 vol% was blown at a flow rate of 40 l / min per 1 kg of calcium hydroxide to suspend the water Carbonation was carried out until the pH of the liquid reached 6.8 (final carbonation step).

  The calcium carbonate suspension thus obtained was dehydrated by a press dehydrator to obtain a press cake having a solid content of 40 to 45% (dehydration step).

  The press cake was pre-dried until the moisture content became 30 to 40%, and then dried and ground by a flash jet dryer to obtain about 70 kg of porous calcium carbonate.

The physical properties of the porous calcium carbonate thus obtained were measured by the following measuring method.
-Bulk specific gravity: According to Ishiyama type measuring instrument.
・ Purity: Conforms to the calcium carbonate section of the official food additives.
-Lead content: According to the section of calcium carbonate in the Food Additives Standards-Average particle size: According to a laser diffraction particle size distribution analyzer SALD-2000J (manufactured by Shimadzu Corporation).
-BET specific surface area: According to Flowsorb II type (manufactured by Shimadzu Corporation). Nitrogen gas was used.
-Pore volume: Based on a porosimeter by mercury porosimetry.
・ Oil absorption: Ogura method.
・ Water absorption: Ogura method.

  The measurement results are shown in Table 1. For comparison, the physical properties of commercially available calcium carbonate (reagent special grade calcium carbonate, product code 030-00385 manufactured by Wako Pure Chemical Industries, Ltd.) are also shown.

  Next, each calcium carbonate of an Example and a comparative example was used for the "calcium balance test by a rat", and the bioabsorption rate of calcium was measured about each calcium carbonate of an Example and a comparative example. The results are shown in Table 2 and Table 3.

The details of this test are as follows.
Experimental animals: 6 animals of each 28-week-old Fisher strain (F344) male rat.
-Breeding feed: According to the standard feed AIN-93M composition, only the calcium source was prepared by changing to each calcium carbonate in Examples and Comparative Examples.
-Breeding period: Preliminary breeding (AIN-93M salary) 1 week. Normal breeding period 31 days.
Evaluation method: Feces and urine were collected on days 24-31 of the normal breeding period, the calcium content was measured, and the calcium absorption, calcium absorption, calcium retention, and calcium retention were calculated (Table 2). Further, after 34 days, the kidney was removed and the amount of calcium was measured (Table 3).

  As shown in Table 2, the bioabsorption rate and retention rate of the rat calcium provided with the calcium carbonate of the example were compared with the bioabsorption rate and retention rate of the calcium of the rat provided with the calcium carbonate of the comparative example, Significantly higher values (P <0.05). Moreover, as shown in Table 3, the amount of calcium in the kidneys of the rats provided with the calcium carbonate of the examples was significantly lower than the amount of calcium in the kidneys of the rats supplied with the calcium carbonate of the comparative example. (P <0.05). From these results, it was found that the calcium carbonate of the example had a high bioabsorption rate and a low possibility of forming stones in the kidney. That is, the calcium carbonate of the examples has a high bioavailability since it has a high bioabsorption rate and is difficult to form a calculus in an organ.

Claims (6)

Carbon dioxide-containing gas having a carbon dioxide concentration of 15% by volume or more is blown into a calcium hydroxide aqueous suspension having a solid content of 5 to 10 wt% and a temperature of 15 to 20 ° C. at a rate of 25 liters / minute or more per 1 kg of calcium hydroxide. A first carbonation step for carrying out a carbonation reaction to a conversion rate of 90% or more;
Water suspension prepared to contain 5 to 20 parts of calcium hydroxide in 100 parts of calcium hydroxide solid content used for preparation of the first carbonation process in the suspension after completion of the first carbonation process. The liquid is added and a carbon dioxide-containing gas having a carbon dioxide concentration of 10% by volume or more is blown at a rate of 15 liters / minute or more per 1 kg of calcium hydroxide, the pH of the suspension is 6.5 to 7.5, and the carbonation rate is 95. A final carbonation step in which the carbonation reaction is carried out until it becomes at least%,
The calcium carbonate aqueous suspension after the final carbonation step is dried at a solid content of 60% or less. The bioabsorption rate of calcium based on a calcium balance test by rats is 10 % Calcium carbonate.   The calcium carbonate according to claim 1, wherein the calcium carbonate aqueous suspension after the final carbonation step is subjected to a dehydration step for dehydration so that the solid content is in a range of 30 to 60%, and then the drying step is performed. .   A suspension prepared so as to contain 5 to 20 parts of calcium hydroxide in 100 parts of calcium hydroxide solid content used in the first carbonation process in the suspension after completion of the first carbonation process. A second carbonation step in which a turbid solution is added and a carbon dioxide-containing gas having a carbon dioxide concentration of 10% by volume or more is blown at a rate of 15 liters / minute or more per 1 kg of calcium hydroxide to carry out a carbonation reaction to a carbonation rate of 70 to 95%. The calcium carbonate according to claim 1 or 2, wherein the final carbonation step is carried out after repeating at least once. Carbon dioxide-containing gas having a carbon dioxide concentration of 15% by volume or more is blown into a calcium hydroxide aqueous suspension having a solid content of 5 to 10 wt% and a temperature of 15 to 20 ° C. at a rate of 25 liters / minute or more per 1 kg of calcium hydroxide. A first carbonation step for carrying out a carbonation reaction to a conversion rate of 90% or more;
Water suspension prepared to contain 5 to 20 parts of calcium hydroxide in 100 parts of calcium hydroxide solid content used for preparation of the first carbonation process in the suspension after completion of the first carbonation process. The liquid is added and a carbon dioxide-containing gas having a carbon dioxide concentration of 10% by volume or more is blown at a rate of 15 liters / minute or more per 1 kg of calcium hydroxide, the pH of the suspension is 6.5 to 7.5, and the carbonation rate is 95. A final carbonation step in which the carbonation reaction is carried out until it becomes at least%,
And drying the calcium carbonate aqueous suspension after the final carbonation step in a state where the solid content is 60% or less.   The calcium carbonate aqueous suspension after the final carbonation step further includes a dehydration step of dehydrating so that the solid content is in the range of 30 to 60%. In the drying step, the calcium carbonate water after the dehydration step is The method for producing calcium carbonate according to claim 4, wherein the suspension is dried.   A suspension prepared so as to contain 5 to 20 parts of calcium hydroxide in 100 parts of calcium hydroxide solid content used in the first carbonation process in the suspension after completion of the first carbonation process. A second carbonation step in which a turbid solution is added and a carbon dioxide-containing gas having a carbon dioxide concentration of 10% by volume or more is blown at a rate of 15 liters / minute or more per 1 kg of calcium hydroxide to carry out a carbonation reaction to a carbonation rate of 70 to 95%. The method for producing calcium carbonate according to claim 4 or 5, wherein the final carbonation step is performed after the second carbonation step is repeated one or more times.