JPH0218830B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for sterilizing powder and granules, and more particularly to a method for sterilizing powder and granules that are raw materials or products for foods, medicines, spices, etc., without altering or damaging them. [Prior Art] Conventionally, heat sterilization, chemical sterilization, radiation sterilization, and the like have been used as methods for sterilizing raw materials or products such as foods, medicines, and spices to improve their safety and preservability. Here, the heat sterilization method generally uses flame, steam, hot water, superheated steam, hot air, etc. as a heat source and is carried out at a high temperature of 60 to 130 degrees Celsius. , destruction of flavor components, discoloration, etc. often occur, resulting in a decline in product quality and even the loss of the functionality that the product should have. Therefore, it is necessary to strictly control the sterilization temperature, sterilization time, and even the cooling time after sterilization. In particular, when the product is a powder or granular material, it is difficult to uniformly heat the product and rapidly cool it after sterilization. Further, a typical chemical sterilization method is a gas sterilization method using ethylene oxide. This method has the advantage of being able to sterilize at low temperatures and sterilizing the powdered raw material while it is still in the box or bag. However, the chemical ethylene oxide is highly toxic and its residue is a problem, It is only approved for sterilizing medical instruments and sanitary materials, but cannot be used for sterilizing food. Under the Food Sanitation Act, chlorine-based disinfectants such as hypochlorous acid and bleached powder, and hydrogen peroxide are permitted as synthetic disinfectants, but chlorine-based disinfectants are limited to sterilizing drinking water, and peroxide The condition is that hydrogen must be completely decomposed and removed. As described above, since the chemical sterilization method uses toxic chemicals, there is a problem of their remaining in the product, and there is also a possibility that they may react with the product itself and alter the quality of the product, which limits its use. Furthermore, cobalt-60 or cesium-137 gamma rays are used in radiation sterilization methods. Although a joint expert committee of the Food and Agriculture Organization of the United Nations, the International Atomic Energy Agency, and the World Health Organization of the United Nations concluded that there is no problem with the toxicity of irradiation at a total average dose of 1 megarad or less, Japan However, its use is only permitted in some foods. Also, depending on the degree of radiation irradiation, the product may have a strange odor,
Discoloration, softening of tissues, and destruction of nutrients may occur, and handling and management of sterilization equipment is also difficult. [Problems to be solved by the invention] As described above, conventional sterilization methods such as heat sterilization, chemical sterilization, and radiation sterilization make it difficult to sterilize powder while maintaining its quality. Problems such as chemical residue and equipment handling management remain unresolved. The present invention has been made against the background of the above-mentioned conventional technical problems, and is capable of easily sterilizing powdered products without causing deterioration in quality such as deterioration or discoloration, has no residual toxicity, and is easy to use in equipment. The purpose of the present invention is to provide a method for sterilizing powder and granular materials that is easy to handle and manage. [Means for Solving the Problems] That is, the present invention is characterized by contacting the granular material with carbon dioxide of 50 to 400 Kg/cm ² G and 10 to 40° C. in the presence of water and/or ethanol. The present invention provides a method for sterilizing powder and granular materials. In the present invention, powder and granules include grains, spices,
Powders or granules of raw materials or products such as crude drugs, enzymes, bacterial preparations, processed foods, pharmaceuticals, and cosmetics. The carbon dioxide used in the present invention has a pressure of
50-400Kg/ ^cm2G , preferably 100-300Kg/ ^cm2G
and the temperature is 10 to 40°C, preferably 30 to 40°C. At this time, carbon dioxide is in a liquid or supercritical state. If the pressure of carbon dioxide is less than 50 Kg/cm ² G, sterilization may not be sufficient, while if it exceeds 400 Kg/cm ² G, the sterilizing effect will not increase proportionally, and the pressure will be too high, causing the device to fail. may cause problems. Furthermore, if the temperature of carbon dioxide is less than 10°C, the sterilizing effect may not be sufficient, while if it exceeds 40°C, it may lead to deterioration of the powder or granular material that is the raw material or product. In the present invention, the granular material is sterilized by contacting with such high-pressure carbon dioxide, but it is essential to carry out the sterilization in the presence of water and/or ethanol. A sufficient sterilizing effect will not be produced if the granular material is brought into contact with only high-pressure carbon dioxide, and a surprising sterilizing effect will only be produced in the presence of water and/or ethanol. Here, when bringing the granular material into contact with high-pressure carbon dioxide, the means for making water and/or ethanol present in the contact treatment is, for example, by pre-containing water in the granular material or by applying high-pressure carbon dioxide. This is carried out by incorporating ethanol into the mixture. In the former case, the concentration of water pre-contained in the powder is usually such that the water content of bacteria living in the powder is 10 to 95% by weight, preferably 70 to 90% by weight. Adjust in advance. The moisture concentration of the bacterial cells in the powder is calculated using the following formula, using the powder containing the bacteria as a sample, that is, assuming that the moisture concentration of the powder is that of the bacterial cells. Moisture concentration (%) = Initial sample weight - Sample weight after drying / Sample weight after drying x 100 (Here, "initial sample weight" is the weight of the humidity-conditioned sample after spraying and mixing water, "Sample weight after drying"
is the weight of the product dried in a constant temperature oven at 105℃ until the temperature is constant. ) In the latter case, the ethanol concentration contained in the high-pressure carbon dioxide is usually 1
-10% by weight, preferably 1-3% by weight. In both of the above cases, if the concentration of water or ethanol is less than the above range, the sterilizing effect on the powder or granules will be poor, while if it is higher than the above range, drying and ethanol removal operations will be required after the sterilization treatment. becomes. In the method for sterilizing powder or granular materials of the present invention, a combination of water and/or ethanol and high-pressure carbon dioxide is an essential requirement, and the object of the present invention cannot be achieved without any of these. For example, even if a powder or granular material is contact-treated with low-pressure carbon dioxide gas containing ethanol, the treatment time will be long and the sterilization effect will not be sufficient. In the present invention, by using high-pressure carbon dioxide in a liquid or supercritical state, it can act even inside the powder or granule material in a short time, and by making water and/or ethanol present at this time, The sterilizing effect has been dramatically improved compared to conventional methods, and since low-temperature, high-pressure carbon dioxide is used, there is no quality deterioration such as deterioration or discoloration of the powder or granules. That is, when high-pressure carbon dioxide and water are used together, it is thought that the carbon dioxide and water react during contact treatment to form carbonic acid, which lowers the pH of the treatment system and promotes the bactericidal action. When high-pressure carbon dioxide and ethanol are used together, it is thought that the sterilizing effect that ethanol originally has is significantly improved by high-pressure carbon dioxide. In addition, in the present invention, the granular material is mixed with water and/or
Alternatively, the treatment time when contacting with high pressure carbon dioxide in the presence of ethanol is not particularly limited, but is usually 10 minutes to 4 hours, preferably 30 minutes to 2 hours. Hereinafter, the present invention will be explained in more detail using the drawings. FIG. 1 is an embodiment of the present invention, and is a flow sheet of a sterilization apparatus for powder and granular materials. In Figure 1, the powder and granular materials that require sterilization are
It is filled into a sterilization tank 1, which is a high-pressure autoclave equipped with a temperature control function. At this time, the powder or granular material may be filled into the sterilization tank 1 as is, or it may be filled in advance into a basket-shaped inner cylinder or a bag or container for storing the powder and granular material, and this may be filled into the sterilization tank 1. It may be placed. At this time, the powder or granular material is filled into the sterilization tank 1 as it is without adjusting its moisture content, or after its moisture content has been adjusted in advance. Whether or not to adjust the moisture content of the powder or granule in advance is selected depending on the condition of the bacteria present in the powder or granule, especially the water content of the bacteria, and the purpose of sterilization, but it is not recommended to use ethanol as a sterilizer. In this case, it is necessary to adjust the moisture content of the powder or granules, that is, the moisture content of the bacterial cells present in the powder or granules, in advance within the above range. In this case, it goes without saying that if the powder itself contains an appropriate amount of water, there is no need to adjust the water content in advance. In this way, the sterilization tank 1 is filled with powder and granules, and then high-pressure carbon dioxide in the above pressure and temperature range is supplied to the bottom of the sterilization tank 1 via the carbon dioxide pump 2, and the powder and granules are brought into contact with each other. Process. At this time, when ethanol is present in high-pressure carbon dioxide, it is passed through the mixer 4 from the ethanol pump 3,
Ethanol is mixed into the high-pressure carbon dioxide. In this contact treatment, sterilization is carried out by leaving the material in this state for the treatment time, but in order to efficiently bring the powder and granules into contact with water and/or ethanol and high-pressure carbon dioxide, the circulation pump 5 is used to connect the circulation line. 6
It is also possible to circulate high-pressure carbon dioxide while keeping it within the pressure and temperature range of the present invention. Next, after sterilization is carried out for a predetermined period of time, the valve 6 is opened to reduce the pressure, and the sterilized powder and granular material can be taken out. Note that the carbon dioxide, ethanol, etc. used for sterilization at this time can be recovered by a separator, liquefier, etc. (not shown) and used again. [Example] Hereinafter, the present invention will be explained in more detail with reference to Examples. Example 1 and Comparative Example 1 Using the powder sterilizer shown in Fig. 1, rice bran (moisture content: 13.7% by weight) was filled into sterilization tank 1, and the rice bran was put under pressure.
High-pressure carbon dioxide at a pressure of 200 kg/cm ² G and a temperature of 40° C. was supplied to the sterilization tank 1, and the treatment was carried out for 2 hours while maintaining this pressure and temperature. Note that the circulation line 6 was not used. When treated rice bran and untreated rice bran were each sealed in glass bottles and stored at room temperature for 6 months, the treated rice bran did not change in quality at all (Example 1).
In the untreated product, blue mold grew and the whole product deteriorated and rotted (Comparative Example 1). Examples 2 to 5 and Comparative Examples 2 to 3 In order to confirm the bactericidal effect of high-pressure carbon dioxide or a mixture of carbon dioxide and ethanol, baker's yeast, Escherichia coli, Staphylococcus aureus, black mold, and Bacillus subtilis were tested in Figure 1. It was sterilized by various methods using the same equipment. (1) Using bacterial cells adjusted to a moisture content of 70 to 90% by weight,
Contact treatment was carried out in the same manner as in Example 1 using high-pressure carbon dioxide at a pressure of 200 Kg/cm ² G and a temperature of 35°C. The results are shown in Table 1. The survival rate of bacterial cells after contact treatment was 1/100,000 to 1/10 million (Example 2). On the other hand, bacteria with less water content (2~
9% by weight) was subjected to contact treatment in the same manner, and the survival rate of the bacterial cells was high (Comparative Example 2). (2) Using black mold and Bacillus stearothermophilus with a moisture content of 2 to 20% by weight,
Pressure 200Kg/cm ² G, including weight% ethanol.
Contact treatment was carried out in the same manner as in Example 1 using high-pressure carbon dioxide at a temperature of 35°C. The results are shown in Table 2. Although the survival rate of Bacillus stearothermophilus is slightly higher, it can be seen that all bacteria have a sufficient bactericidal effect (Example 3). On the other hand, it can be seen that the high-pressure carbon dioxide containing no ethanol has insufficient bactericidal effect (Comparative Example 3). (3) Using black mold and Bacillus stearothermophilus adjusted to a moisture content of 70 to 90% by weight, and containing high-pressure carbon dioxide at a pressure of 200 Kg/cm ² G and a temperature of 35°C or 2% by weight of ethanol. Contact treatment was carried out in the same manner as in Example 1 using high-pressure carbon dioxide at a pressure of 200 Kg/cm ² G and a temperature of 35°C. The results are shown in Table 3. Even when ethanol is not contained in carbon dioxide, there is a bactericidal effect due to the synergistic effect with water (Example 4), but when ethanol is also added to high-pressure carbon dioxide, the bactericidal effect is particularly enhanced against black mold. I understand (Example 5).

【table】

【table】

[Table] Examples 6, 7 and Comparative Example 4 The same procedure as in Example 1 was carried out, except that Escherichia coli whose water concentration was adjusted to 65 to 75% by weight was used, and the temperature was 20°C and the pressure was treated with carbon dioxide as shown in Table 4. contact treatment. The survival rate of bacterial cells after treatment is shown in Table 4.

[Table] Examples 8, 9 and Comparative Example 5 Example 1 except that baker's yeast whose water concentration was adjusted to 65 to 75% by weight was used and the temperature was 35°C and the pressure was treated with carbon dioxide as shown in Table 5. Contact treatment was carried out in the same manner. Table 5 shows the survival rate of the bacterial cells after the treatment.

[Table] Examples 10, 11 and Comparative Example 6 Using the powder sterilizer shown in Figure 1, koji (moisture content
29.4% by weight) is filled into sterilization tank 1, and the pressure is applied to this tank.
Supplying high pressure carbon dioxide (Example 10), high pressure carbon dioxide and 2% by weight ethanol (Example 11), or high pressure air (Comparative Example 6) at 300 Kg/cm ² G and a temperature of 40°C to the sterilization tank 1, The treatment was continued for 2 hours while maintaining this pressure and temperature. Note that the circulation line 6 was not used. Table 6 shows the number of microorganisms after treatment.

〔Effect of the invention〕

According to the present invention, since water and/or ethanol and high-pressure carbon dioxide, which are harmless to the human body and have low reactivity, are used as disinfectants, there are no problems such as generation of strange odor, discoloration, destruction of tissue nutrition or function, etc. Grains, spices, without quality loss
It is possible to sterilize powder and granular materials, which are raw materials and products for crude drugs, enzymes, bacterial preparations, processed foods, pharmaceuticals, cosmetics, etc., at low temperatures and in a short time, and is of great industrial significance.

[Brief explanation of drawings]

FIG. 1 is an embodiment of the present invention, and is a flow sheet of a sterilization apparatus for powder and granular materials. 1; Sterilization tank, 2; Carbon dioxide (CO ₂ ) pump,
3; ethanol pump, 4; mixer, 5; circulation pump, 6; circulation line, 7; valve.

Claims (1)

[Scope of Claims] 1. A method for sterilizing powder or granular material, which comprises contacting the powder with carbon dioxide at 50 to 400 Kg/cm ² G and 10 to 40° C. in the presence of water and/or ethanol. 2 Pre-contain water in the powder and then add 50% water to it.
-400Kg/ ^cm2G , 10-40℃ carbon dioxide or 50-400Kg/ ^cm2G , 10-40℃ carbon dioxide containing ethanol is brought into contact with sterilization of the granular material according to claim 1 Method. 3 The water concentration of bacteria present in the powder is 10 to 95
A method for sterilizing powder or granular material according to claim 1 or 2, wherein the sterilization method is adjusted to % by weight. 4. The method for sterilizing powder or granular material according to any one of claims 1 to 3, wherein the concentration of ethanol in carbon dioxide is 1 to 10% by weight.