Method for preparing packaged sterilized mineral water, method for producing sterilized container for packaging the same and packaged sterilized mineral water

Sterilized and packaged mineral water comprises sterilized mineral water having a hardness of not less than 50 mg/l and a content of dissolved carbonic acid gas ranging from 9 to 30 mg/l (as calcium carbonate) and a number of bacteria of not more than 10.sup.-3 /ml which is obtained by sterilizing pumped-up mineral water having a hardness of not less than 50 mg/l and a content of dissolved carbonic acid gas ranging from 10 to 31 mg/l by filtering through a filter having a pore size of not more than 0.22 .mu.m. The packaged and sterilized mineral water can be effectively prepared by a method which comprises packaging pumped-up mineral water in a container without subjecting it to any heat-sterilization treatment wherein the mineral water is sterilized by passing through a filter having a pore size of not more than 0.22 .mu.m, packaged in a sterilized container under an aseptic condition of not more than Class 100 and then the container is airtight-sealed. Thus, packaged and sterilized mineral water having excellent keeping quality can be obtained without subjecting pumped-up mineral water to any sterilization by heating and without using any antibacterial agent and it has a high hardness and a high carbon dioxide content as well as good taste peculiar to the original mineral water.

BACKGROUND OF THE INVENTION 
The present invention relates to a method for preparing sterilized mineral 
water without any heat-sterilization treatment, the mineral water being 
preferably free of an antibacterial agent and packaged in a container such 
as a bottle; a method for producing a container for packaging the mineral 
water; and the packaged mineral water per se. 
There has been a demand for water having good taste and special water 
originated from various places have been packaged in containers and put on 
the market in great quantities. Since there is a possibility of 
propagation or proliferation of bacteria in pumped up, naturally occurring 
mineral water, there has, in general, been added chlorine to the pumped up 
mineral water to inhibit the subsequent propagation of bacteria (see 
Japanese Patent Unexamined Publication (hereinafter referred to as "J.P. 
Kokai") No. Sho 57-32779). However, it has been believed that if chlorine 
is added to mineral water, not only the natural taste of mineral water is 
deteriorated but also harmful substances such as trihalomethane are formed 
from the residual chlorine. On the other hand, there has been proposed a 
method in which mineral water is treated with chlorine and then with 
active carbon, but the natural taste pecuriar to each mineral water is 
impaired. Sterilization by heating is also an effective means, but the 
taste peculiar to each mineral water is likewise impaired. 
Mineral water of high quality, in particular that having good taste has a 
high hardness and contains a large amount of carbon dioxide. However, if 
mineral water having a high hardness is subjected to the foregoing thermal 
sterilization treatment, components such as Ca and Mg which serve to 
increase the hardness of water in the form of bicarbonates are converted 
into carbonates, i.e., water-insoluble calcium or magnesium carbonates and 
thus precipitated out from the water and as a result, the hardness of 
water is greatly lowered. 
Under such circumstances, there has been a need for the development of a 
method for preparing packaged mineral water in which pumped up mineral 
water is packaged in a container such as a bottle without addition of any 
antibacterial agent and without performing any thermal sterilization 
treatment and thereby the proliferation of bacteria in the mineral water 
is effectively prevented. 
On the other hand, plastic bottles such as bottles of polyethylene 
terephthalate (PET) used for packaging mineral water have been generally 
sterilized by spraying an antibacterial agent such as hydrogen peroxide on 
the external and internal walls of the bottles. However, this method 
suffers from problems such that the taste of the contents thereof is 
impaired and that the residual antibacterial agent is bad for health of 
the persons who eat or drink the contents since a trace amount of the 
antibacterial agent remains unremoved on the walls of the bottle. 
Thus, various attempts have been directed to the development of solutions 
of these problems. For instance, J.P. Kokai No. Sho 63-138931 discloses a 
method which comprises a sterilization-drying process in which an 
antibacterial agent is sprayed on a container and then hot air is blown 
onto the container to dry the same and a washing process for removing and 
washing away the antibacterial agent adhered to the external and internal 
walls of the container. In addition, J.P. Kokai No. Sho 60-99828 proposes 
a method comprising the step of spraying a solution of an antibacterial 
agent and then a washing solution on a container. However, in these 
methods, a large amount of washing solution is required for completely 
removing the antibacterial agent and the processes are very complicated. 
SUMMARY OF THE INVENTION 
A first object of the present invention is to provide a method for 
preparing packaged and sterilized mineral water having excellent keeping 
quality without subjecting pumped-up mineral water to any sterilization 
treatment by heating. 
A second object of the present invention is to provide a method for 
preparing packaged and sterilized mineral water having excellent keeping 
quality without addition of any antibacterial agent to pumped-up mineral 
water. 
A third object of the present invention is to provide a method for 
preparing sterilized mineral water which makes it possible to effectively 
prevent proliferation of bacteria in mineral water till the mineral water 
is packaged in a container such as a bottle after pumping up the mineral 
water without addition of any antibacterial agent. 
A fourth object of the present invention is to provide a method for 
producing a sterilized container such as a bottle for packaging the 
sterilized mineral water which makes it possible to simply and efficiently 
sterilize the container without use of an antibacterial agent. 
A fifth object of the present invention is to provide packaged and 
sterilized mineral water having a high hardness and a high carbon dioxide 
content as well as good taste and good keeping quality. 
These and other objects of the present invention will be apparent from the 
following description and Examples. 
According to a first aspect of the present invention, there is provided a 
method for preparing packaged and sterilized mineral water which comprises 
pumping up mineral water and then packaging the mineral water without 
subjecting it to any heat-sterilization treatment wherein the mineral 
water is sterilized by passing through a filter having a pore size of not 
more than 0.22 .mu.m, packaged in a sterilized container under an aseptic 
condition of not more than Class 100 and then the container is 
airtight-sealed. 
According to a second aspect of the present invention, there is provided a 
method for producing a sterilized plastic bottle for packaging sterlized 
mineral water which comprises the steps of standing a plastic bottle 
upside down, inserting a hot water-injecting nozzle into the bottle though 
an opening of the bottle, upwardly injecting hot water through the nozzle 
so that the injected hot water is discharged from the opening through the 
bottom and the side wall of the bottle to thus elevate the temperature of 
the inner wall of the bottle to a sterilization temperature. 
According to a third aspect of the present invention, there is provided 
sterilized and packaged mineral water comprising sterilized mineral water 
having a hardness of not less than 50 mg/l and a content of dissolved 
carbonic acid gas ranging from 9 to 30 mg/l (as calcium carbonate) and a 
number of bacteria of not more than 10.sup.-3 /m l which is obtained by 
sterilizing pumped-up mineral water having a hardness of not less than 50 
mg/l and a content of dissolved carbonic acid gas ranging from 10 to 31 
mg/l by filtering through a filter having a pore size of not more than 
0.22 .mu.m.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In the present invention, mineral water sterilized by passing through a 
filter having a pore size of not more than 0.22 .mu.m is packaged in a 
sterilized container under an aseptic condition of not more than Class 100 
and then airtight-sealed. 
More specifically, pumped-up mineral water is desirably passed through a 
filter having a pore size of not more than 0.22 .mu.m under the conditions 
for filtration of, for instance, an operating pressure ranging from about 
1.0 to 2.0 kg/cm.sup.2 and a flow rate of water ranging from about 5 to 20 
l/min.m.sup.2. According to this method, mineral water is not subjected to 
any heating process and, therefore, the taste of the mineral water is not 
deteriorated and hence the taste peculiar thereto can effectively be 
maintained. In other words, the filtration of mineral water through a 
filter having a pore size of not more than 0.22 .mu.m permits effective 
removal of any bacteria present in the mineral water and thus the 
sterilization effect comparable to that achieved by high temperature 
heat-sterilization can be ensured. As the filer, there can be used a depth 
filter, membrane filter or the like in a suitable industrial manner such 
as cartridge type. 
Incidentally, the pumped-up mineral water is in general stored in a tank 
after pumping up the same or transported by a tank truck to a packaging 
plant and then packaged in a container. Accordingly, bacteria possibly 
proliferate in the pumed-up mineral water during the storage and/or 
transportation. For this reason, pumped-up mineral water is preferably 
cooled at a temperature of not more than 12.degree. C., preferably not 
more than 10.degree. C. and in particular not more than 5.degree. C. after 
the mineral water is pumped up till it is packaged in a container in order 
to prevent the proliferation or propagation of bacteria. In this 
connection, the lower limit of the cooling temperature is more than the 
freezing point of the mineral water. The temperature of mineral water 
pumped up from a groundwater zone is approximately constant in the order 
of 15.degree. to 17.degree. C. throughout the year, but a variety of 
bacteria are present in the pumped-up mineral water depending on the 
sources thereof or through the contamination with the bacterial present in 
the air during pumping up operations. For this reason, the foregoing 
treatment under the conditions specified above is needed. 
Preferably, the foregoing cooling operation is compulsorily performed 
immediately after mineral water is pumped up from a ground-water zone. 
The foregoing cooling treatment may be performed by the usual manner, but 
preferably carried out using a plate type refrigeration machine. 
Morever, it is preferable that the pumped-up mineral water be filtered 
through a filter having a pore size of not more than 0.45 .mu.m to 
compulsorily remove bacteria such as gram-negative bacteria possibly 
present in the water and water-insoluble matter. This method is preferable 
since harmful miocroorganisms can be removed prior to the subsequent 
sterilization treatment (i.e., the foregoing filtration treatment through 
a filter having a pore size of not more than 0.22 .mu.m). This filtration 
treatment can be performed, for instance, in the same manner as described 
above in connection with the filtration by a filter having a pore size of 
not more than 0.22 .mu.m. As such filters, there may be used, for 
instance, commercially available microfilters. Among them, preferred are 
those having a pore size of 0.45 .mu.m because they make the filtration 
procedure easier. Either of the foregoing cooling treatment and the 
filtration procedure may be carried out in the method of this invention 
and if a combination of these two treatments is adopted, they may be 
carried out in any order. 
The mineral water subjected to the foregoing treatments is preferably 
maintained at a low temperature of not more than 12.degree. C. till it is 
subjected to a sterilization treatment. Therefore, when the mineral water 
is transported by a tank truck to a bottling plant, the mineral water is 
preferably maintained at a low temperature defined above during the 
transportation by a tank truck while if it is stored in a storage tank, 
the temperature of the storage tank is preferably maintained at such a low 
level defined above. 
Then the mineral water which has thus been maintained at a low temperature 
is treated with a filtration film having a pore size of not more than 0.22 
.mu.m to completely remove various germs present therein prior to 
bottling. 
In the present invention, the mineral water thus sterilized is packaged in 
a sterilized container in an aseptic atmosphere of not more than Class 100 
and then airtight-sealed. 
In the present invention, a known antibacterial agent such as a chlorine 
atom-containing bactericide may be added to the sterilized mineral water 
in the course of the sterilization treatment or after the treatment, but 
an excellent sterilization effect can be ensured even if any such 
bactericide is not added. Therefore, it is preferred that no bactericide 
be added to the mineral water. 
Moreover, any mineral water obtained from various groundwater zones may be 
used in the present invention as starting materials, but it is desirable 
to use mineral water pumped up from a groundwater zone which has a 
hardness of not less than 50 mg/l, preferably 70 to 120 mg/l and a content 
of free carbonic acid in the form of dissolved carbon dioxide ranging from 
10 to 31 mg/l (as calcium carbonate), preferably 12 to 17 mg/l. This is 
because, if such mineral water is used as starting water and the water is 
sterilized by the filtration as mentioned above, the resulting water has a 
hardness of not less than 50 mg/l, preferably 70 to 120 mg/l, a content of 
free carbonic acid of 9 to 30 mg/l, preferably 11 to 16 mg/l and a number 
of bacteria of not more than 10.sup.-3 /ml, so that the sterilized mineral 
water having high quality, in view of its taste can easily be obtained. 
Therefore, if the hardness and the content of carbon dioxide of starting 
water are less than the lower limits thereof, these properties are 
preferably adjusted so as to fall within the ranges defined above 
respectively. The term "hardness" herein means the overall hardness which 
is the sum of the temporary hardness and the permanent hardness. 
In the present invention, examples of the containers are plastic bottles, 
glass bottles and cans which are sterilized in the usual manner, but they 
are preferably sterilized by heat-treating with moist heat under the 
following conditions. This is because the resulting mineral water is not 
contaminated with any antibacterial agent since the sterilization 
treatment does not requires the use of an antibacterial agent. 
For instance, if a bottle is used as a container and it is sealed with a 
cap, the bottle and the cap are wet-sterilized such that the inner walls 
thereof are maintained under conditions equivalent to exposure to a 
temperature of 70.degree. C. for 10 seconds or more severe conditions, 
provided that the temperature is not higher than the heat-resisting 
temperature of the bottle and the cap. In this respect, the conditions 
equivalent to exposure to a temperature of 70.degree. C. for 10 seconds 
can be obtained from the following formula: 
EQU log y=1-(x-70)/10 
(wherein x represents the temperature (.degree.C.) of the inner wall of a 
bottle or cap and y means a retention time (seconds)). 
In general, the heat-resisting temperature of plastic bottles and caps is 
low. Accordingly, they can be effectively sterilized under these 
conditions without causing any deformation. In this respect, if the 
sterilization is performed under the conditions corresponding to heating 
at less than 70.degree. C. for less than 10 seconds, a satisfactory 
sterilization effect cannot often be achieved. A better sterilization 
effect can be ensured if a bottle and a cap are treated under the 
conditions such that the inner wall of the bottle or cap is maintained at 
75.degree. C. or higher or under the conditions corresponding to heating 
at a temperature of not less than 75.degree. C. for not less than 10 
seconds. 
Examples of bottles to be sterilized according to the method of this 
invention include plastic bottles oriented by blow molding such as those 
of polyethylene, polypropylene and polyethylene terephthalate (PET). 
Particularly preferred are those made of PET. In addition, examples of 
caps include those formed from plastic materials listed above and those 
made from metals such as aluminum. Among these, preferred are those formed 
from aluminum. 
Upon subjecting the foregoing bottle to wet-sterilization, preferably used 
is a method which comprises the steps of standing a plastic bottle upside 
down, inserting a hot-water injection nozzle into the bottle through an 
opening of the bottle, upwardly injecting hot water through the nozzle so 
that the injected hot water is discharged from the opening through the 
bottom and the side wall of the bottle to thus elevate the temperature of 
the inner wall of the bottle to a sterilization temperature. For instance, 
as shown in FIG. 1, an opening 2 of a bottle 1 is directed towards 
downward direction, preferably just downward direction and a hot-water 
injection nozzle 3 is inserted into the bottle 1 through the opening 2. 
Then hot water is upwardly injected through the nozzle 3 so that the 
injected hot water 4 is discharged from the opening 2 through a bottom 
wall 5 and a side wall 6 of the bottle to thus elevate the temperature of 
the inner wall of the bottle to a sterilization temperature. At this 
stage, the hot-water injection nozzle 3 is inserted into the bottle 1 so 
that the tip of the nozzle 3 does not come in contact with the hot water W 
which flows down through the bottom and the side wall of the bottle 1. 
More specifically, according to this method, the hot water injected 
through the nozzle 3 does not come in contact with the hot water W which 
comes in contact with the inner wall of the bottle and flows down towards 
the opening of the bottle and, therefore, the tip of the hot-water 
injection nozzle is not contaminated and the hot water carrying a desired 
quantity of heat can be effectively supplied to the wall of the bottle. 
Thus, the method makes it possible to steadily elevate the temperature of 
the inner wall of the bottle up to the sterilization temperature. 
Moreover, if a cylindrical hot-water injection nozzle 3 is employed, the 
hot water can effectively flow down through the bottom and the side wall 
of the bottle 1. 
To achieve the sterilization conditions defined above, a cylindrical nozzle 
1 having an inner diameter of 8 to 10 mm, preferably 9 to 10 mm is used as 
the hot-water injection nozzle 3 and hot water having a temperature of the 
bottle 1 is desirably injected into the bottle. In this case, the overall 
amount of the hot water to be injected having a temperature ranging from 
75.degree. to 90.degree. C. ranges from 0.2 to 2 times, preferably 0.5 to 
1 time that of the inner volume of the bottle to be sterilized and the hot 
water is preferably injected through the nozzle 3 at a rate ranging from 
10 to 30 l/min. Thus, the inner wall of the bottle can be effectively and 
uniformly sterilized. 
On the other hand, the moist heat-sterilization of caps can be performed 
by, for instance, injecting hot water into the caps as in the 
sterilization of bottles, passing the caps through hot water or coming the 
caps in contact with steam or hot air. For instance, a metal cap is 
preferably sterilized by coming the inner wall thereof in contact with 
steam and, in this case, the metal cap may also be sterilized by passing 
through a steam tunnel maintained at a temperature ranging from 95.degree. 
to 100.degree. C. for a retention time ranging from about 3 to 15 seconds. 
Satisfactory sterilization and simultaneous washing of these bottles and 
caps can be performed by carrying out the sterilization treatment of them 
according to the foregoing methods, but the temperature of the inner walls 
of the bottle and cap is raised to a desired sterilization temperature by 
the action of hot water while heating the external walls thereof to thus 
maintain the temperature of them at the sterilization temperature for a 
desired time period in order to further improve the sterilization 
efficiency. Specifically, the external walls of the bottle and cap are 
preferably heated by coming in contact with hot water, steam or hot air. 
In particular, when the external wall is heated with hot water, it is 
effective that the hot water is sprayed on the bottle from the upper side 
and/or from the right and left side thereof. This method is more 
preferable than those in which steam or hot air is employed, in that the 
temperature control is relatively easy and that the deformation of the 
bottle can effectively be prevented. Moreover, the method for spraying hot 
water from the upper side of the bottle is preferred because the heat of 
the hot water is uniformly transferred to the external wall of the bottle. 
The foregoing can likewise be applied to the treatment of caps. 
If the foregoing external sterilization treatment is carried out while the 
sterilization temperature attained by the internal sterilization treatment 
has still been maintained, the bottle is further maintained at the 
sterilization temperature, for instance, ranging from 70.degree. to 
90.degree. C. for an additional predetermined time. 
In the foregoing method, hot water having a temperature ranging from 
70.degree. to 95.degree. C., preferably 75.degree. to 95.degree. C. is 
sprayed on the external wall of the bottle for 1 to 20 seconds, preferably 
3 to 15 seconds in an amount ranging from 10 to 1,000 l per bottle. When 
steam is used instead of hot water, steam having a pressure ranging from 
0.2 to 0.5 kg/cm.sup.2 (gauge pressure) is preferably sprayed onto the 
external wall of the bottle for 3 to 15 seconds, while if hot air is 
employed, hot air having a temperature ranging from 80.degree. to 
100.degree. C. is preferably blown on the external wall of the bottle for 
3 to 15 seconds. 
A combination of internal and external sterilization treatments is adopted 
in the foregoing method and, therefore, quite efficient and complete 
sterilization can be accomplished. 
Industrially, the foregoing sterilization treatment of bottles can be 
performed continuously with the aid of, for instance, an apparatus 10 as 
shown in FIG. 2. In FIG. 2, the numerical value 11 represents a conveying 
device and a bottle 1 is transported towards the carrying direction shown 
in the figure while hot water is injected in the bottle through a 
hot-water injection nozzle 3 and sprayed onto the bottle from the upper 
side thereof through a hot-water shower portion 12. 
Most preferably, the foregoing sterilized mineral water is packaged in a 
bottle which has been sterilized according to the foregoing method and 
airtightly sealed with a cap which has been sterilized in the same manner. 
As has been discussed above in detail, according to the present invention, 
there can be provided a method for preparing packaged and sterilized 
mineral water excellent in keeping quality, in which pumped-up mineral 
water as a starting material is not sterilized by heating and any 
antibacterial agent is not used at all. Thus, the method of the present 
invention can provide excellent mineral water whose natural taste can be 
well-maintained. 
The present invention will hereunder be explained in more detail with 
reference to the following non-limitative working Examples. 
EXAMPLE 1 
(i) Sterilization Treatment of Bottle 
A PET bottle having an inner volume of 1,500 cc, a shape similar to that 
shown in FIG. 1 and an opening part having an inner diameter of 21 mm was 
subjected to internal and external washing treatments under the conditions 
detailed below with the aid of an apparatus as shown in FIG. 2. 
Internal Washing Treatment 
The PET bottle was fixed to a conveying device while standing the bottle 
upside down, a hot-water injection nozzle was inserted into the bottle 
through the opening at the region of this side of FIG. 2 in which the 
bottle was conveyed on a circle and the hot water was upwardly injected 
therein so that the hot water was discharged from the opening through the 
bottom and side wall of the bottle. The hot-water injection treatment was 
performed by injecting 1,200 cc of hot water having a temperature of 
85.degree. C. through the nozzle at a rate of 13,000 cc/min. The hot-water 
injection nozzle used herein was a cylindrical nozzle having an inner 
diameter of 9 mm. The foregoing treatment was performed so that the inner 
wall of the bottle was maintained at 80.degree. C. for 3 seconds. 
External Washing Treatment 
The PET bottle was transferred from the foregoing position to a position 
for spraying hot water, 10,000 cc of hot water was sprayed for 5 seconds 
onto the bottle through a shower board disposed above the bottle to 
perform external washing to thus obtain a bottle which was sterilized 
completely from the viewpoint of microorganisms. The external washing was 
started at the second half of the internal washing. 
Sterilization Treatment of Cap 
An aluminum cap having an inner diameter of 28 mm .phi. and a height of 18 
mm was supplied to a sterilizing chamber in its standing state and the 
whole surface of the cap was brought into contact with steam of 
100.degree. C. for 5 seconds to perform sterilization of the cap. The 
inner wall of the cap was maintained at 80.degree. C. for 3 seconds by the 
foregoing treatment. 
Sterilization Treatment of Mineral Water 
Mineral water pumped up from a well (the temperature thereof immediately 
after pumping up was 17.degree. C.) was filtered through a filter cloth to 
remove foreign substance. The mineral water was cooled down to 5.degree. 
C. immediately after pumping up the same using a plate type refrigeration 
machine. The cooled mineral water was subjected to precision filtration by 
passing through a filter having a pore size of 0.45 .mu.m. The mineral 
water thus treated was transported to a bottling plant and stored in a 
storage tank in the bottling plant. The mineral water was maintained at a 
temperature of not more than 10.degree. C. from its pumping up till it was 
introduced into the storage tank and during storage in the tank. 
The mineral water which had been stored for about 8 hours in the storage 
tank was treated with active carbon, subjected to precision filtration by 
passing through a filter having a pore size of 0.22 .mu.m, packaged in the 
PET bottle sterilized above under the aseptic condition of not more than 
class 100 and sealed with the cap likewise sterilized above to give 
packaged sterilized mineral water. 
The resulting mineral water could be stored for about 18 months at ordinary 
temperature without any trouble and, for instance, it maintained the taste 
peculiar thereto even after 12 months storage at ordinary temperature. 
EXAMPLE 2 
Mineral water pumped up from a well (the temperature thereof immediately 
after pumping up was 17.degree. C.) was filtered through a filter cloth to 
remove foreign substance. The mineral water was cooled down to 5.degree. 
C. with the aid of a plate type refrigeration machine immediately after 
pumping up the same. The cooled mineral water was stored in a storage 
tank. The mineral water was maintained at a temperature of not more than 
100.degree. C. from its pumping up till it was introduced into the storage 
tank and during storage in the tank. 
The mineral water which had been stored for about 4 hours in the storage 
tank was treated with active carbon; filtered to sterilize the mineral 
water in the same manner used in Example 1, packaged in a synthetic 
resin-bottle likewise sterilized in the same manner used in Example 1 
under the aseptic condition of not more than class 100 and sealed with a 
cap likewise sterilized in the same manner used in Example 1 to give 
packaged and sterilized mineral water. 
The resulting mineral water could be stored for about 18 months at ordinary 
temperature without any trouble and, for instance, it maintained the taste 
peculiar thereto even after 12 months storage at ordinary temperature. 
EXAMPLE 3 
Mineral water pumped up from a well (hardness 80 mg/l; content of free 
carbonic acid (dissolved carbonic acid gas) 13 mg/l (as calcium 
carbonate); number of bacteria 30/ml; the temperature thereof immediately 
after pumping up 17.degree. C.) was filtered through a filter cloth to 
remove foreign substance. The mineral water was cooled down to 5.degree. 
C. immediately after its pumping up using a plate type refrigeration 
machine. The cooled mineral water was subjected to precision filtration by 
passing through a filter having a pore size of 0.45 .mu.m with the aid of 
a pressure filtration device. 
The mineral water thus treated was transported to a bottling plant and 
stored in a storage tank in the bottling plant. The mineral water was 
maintained at a temperature of not more than 10.degree. C. from its 
pumping up till it was introduced into the storage tank and during storage 
in the tank. 
The mineral water which had been stored for about 12 hours in the storage 
tank was treated with active carbon, subjected to precision filtration by 
passing through a filter having a pore size of 0.22 .mu.m using a pressure 
filtration device to give sterilized mineral water. The foregoing 
filtration procedure was carried out at 15.degree. C. The resulting 
mineral water had a hardness of 80 mg/l, a content of free carbonic acid 
of 12 mg/l and number of bacteria of not more than 10.sup.-5 /ml. 
The mineral water thus obtained was packaged in a sterilized bottle of a 
synthetic resin under the aseptic condition of not more than class 100 and 
sealed with a sterilized cap to give packaged sterilized mineral water. 
The bottle was sterilized by maintaining at 75.degree. C. for 10 seconds 
using hot water and the cap was sterilized by maintaining at 100.degree. 
C. for 5 seconds using steam. 
The resulting mineral water had a viable count (number of bacteria capable 
of proliferating in the mineral water) of 10.sup.-5 /ml and could be 
stored for about 18 months at ordinary temperature without any trouble 
and, for instance, it maintained the taste peculiar thereto even after 12 
months storage at ordinary temperature. 
EXAMPLE 4 
Mineral water pumped up from a well (hardness 80 mg/l; content of free 
carbonic acid 13 mg/l; number of bacteria 30/ml; the temperature thereof 
immediately after pumping up 17.degree. C.) was filtered through a filter 
cloth to remove foreign substance. The mineral water was then treated with 
activated carbons, subjected to precision filtration by passing through a 
filter having a pore size of 0.22 .mu.m with the aid of a pressure 
filtration device to obtain sterilized mineral water. The filtration was 
carried out at a temperature of 15.degree. C. The thus-obtained mineral 
water had a hardness of 80 mg/l, content of free carbonic acid of 12 mg/l 
and number of bacteria of not ore than 10.sup.-5 /ml. 
The mineral water thus obtained was packaged in a sterilized bottle of a 
synthetic resin and sealed with a sterilized cap under the same conditions 
used in Example 1 to give packaged sterilized mineral water. 
The resulting mineral water had a viable count (number of bacteria capable 
of proliferating in the mineral water) of 10.sup.-5 /ml and could be 
stored for about 18 months at ordinary temperature without any trouble 
and, for instance, it maintained the taste peculiar thereto even after 12 
months storage at ordinary temperature.