Chemical apparatus and process disinfecting – deodorizing – preser – Process disinfecting – preserving – deodorizing – or sterilizing – Using direct contact with electrical or electromagnetic...
Reexamination Certificate
2000-10-04
2002-12-24
Warden, Sr., Robert J. (Department: 1744)
Chemical apparatus and process disinfecting, deodorizing, preser
Process disinfecting, preserving, deodorizing, or sterilizing
Using direct contact with electrical or electromagnetic...
C422S003000, C422S029000, C422S186030
Reexamination Certificate
active
06497839
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a sterilizer and a sterilization method which utilize a high voltage. More particularly, the present invention relates to a sterilizer utilizing a high voltage which can be used for solid products in general, e.g., foods, drugs, Chinese herb medicines, cosmetics, feedstuffs, and fertilizers, and in particular, which can be optimally used for foods unsuitable for being subjected to heating; and a sterilization method utilizing such a sterilizer.
2. Detailed Description of the Prior Art
Conventionally, heat sterilization has been generally employed as a method for sterilizing foods. Heat sterilization, however, causes changes in components, aromas, flavors, colors, etc., the escaping of active ingredients, and the like, thereby deteriorating the qualities of foods.
A method for sterilizing a food by bringing the food into contact with heated water vapor (Japanese Patent Publication No. 63-50984) has been suggested. Where this method is employed, however, changes and deterioration in a food quality are likely to occur because of the loss of an aroma component, the penetration of a water vapor into the food, and the like.
Methyl bromide fumigation has been conducted in order to sterilize rice and kill insects in rice. However, methyl bromide is designated as a dangerous substance due to its high inflammability. Methyl bromide is also designated as a deleterious substance, and a blister is formed when one's skin touches methyl bromide. Therefore, this method lucks in safety. In addition, when methyl bromide is released into the atmosphere and reaches the ozone layer around the globe, methyl bromide depletes the ozone layer due to its high potential to deplete the ozone layer.
Although ozone has been used for sterilization, the obtained sterilization effect is not sufficient. Also, in order to suppress an increase in the number of molds, low temperature storage (e.g., 15° C., 70-75% RH) has been conducted, long-term low temperature storage may cause an increase in the number of molds.
Radiation sterilization which utilizes cobalt-60 or the like is permitted to be used for adzuki bean, corn, spices, and the like. However, such a method requires a large equipment, and thus the equipment cost is high. In addition, shielding is required in order to prevent radiation from leaking to the outside.
If the number of microorganisms, in particular, the number of molds is increased during the storage of unpolished rice, for example, in the worst case scenario, the commercial value of the unpolished rice is lost, and the rice is no longer suitable for eating. It cannot be expected that spore forming bacteria attached to the rice will become extinct even at the time of cooking the rice.
Some foods are not suitable for being subjected to heat sterilization. For example, rice which is a staple food for Japanese people is not suitable for being subjected to heat sterilization or chemical treatments.
SUMMARY OF THE INVENTION
The first object of the present invention is to provide a sterilizer: which can easily and efficiently sterilize various kinds of bacteria, including spore forming bacteria attached to rice, at a room temperature and an atmospheric pressure so as to reduce the number of bacteria, without deteriorating qualities of a flavor, a taste, a beneficial effect, a power, dispersibility, and the like, which are inherent to an object to be sterilized (hereinafter, referred to as “sterilization object”) such as a food, a drug, a Chinese herb medicine, a cosmetic, a feedstuff, and a fertilizer; which does not require pretreatment and/or after-treatment; which is highly safe; and which does not cause the ozone layer depletion problem The second object of the present invention is to provide a sterilization method which can easily, economically and efficiently sterilize various kinds of bacteria, including spore forming bacteria attached to rice, at a room temperature and an atmospheric pressure so as to reduce the number of bacteria by using the above-described sterilizer, without deteriorating qualities of a flavor, a taste, a beneficial effect, a power, dispersibility, and the like, which are inherent to a sterilization object such as a food, a drug, a Chinese herb medicine, a cosmetic, a feedstuff, and a fertilizer.
The inventors of the present invention conducted in-depth studies in order to solve the conventional problems. Consequently, they found that various kinds of bacteria including spore forming bacteria can be sterilized easily, efficiently, and economically by interposing a sterilization object between a discharge side electrode and a ground side electrode to which a high AC voltage or a pulsed high voltage is applied and by causing a pulse streamer discharge between the above-described electrodes at a room temperature and an atmospheric pressure in the atmosphere controlled to have a humidity suitable for sterilization, thereby completing the present invention.
In order to solve the above-described problems, the present invention according to claim
1
is a sterilizer which comprises: a power supply section for generating a high voltage; a processing device having a discharge side electrode and a ground side electrode to which the generated high voltage is applied; and humidity control means for controlling a humidity in the processing device. A sterilization object is interposed between the electrodes of the processing device, and a pulse streamer discharge occurs between the electrodes.
According to the present invention, various kinds of bacteria are sterilized by causing a pulse streamer discharge between the above-described electrodes.
While a corona discharge during the application of a DC voltage causes only the vicinity of the discharge side electrode to emit light, a pulse streamer discharge can excite a much wider area into a plasma state. The reasons for this are as follows. First, a pulse streamer discharge can instantaneously apply a voltage higher than a spark voltage in the case of a DC corona discharge, thereby broadening the high electric field region. Second, while a discharge is suppressed in the case of a DC corona discharge because of a reduced electric field strength in an ionization region near the discharge side electrode due to ionic space charge, discharge suppression due to a space charge electric field is very small in the case of a pulse streamer discharge because of the rapid start-up of the voltage.
The present invention according to claim
2
is characterized in that the discharge side electrode comprises a large number of needle-shaped electrodes which are provided with a predetermined distance apart from one another in the sterilizer according to claim
1
.
If plate-shaped electrodes are respectively used as the discharge side electrode and the ground side electrode, the surface areas thereof are increased. Thus, there is a need to increase the capacity of a power supply section for generating a high voltage. Also, both of the plate-shaped electrodes need to be absolutely parallel to each other. If the parallel state is not maintained, a discharge occurs only in a certain area. In the case where a needle-shaped electrode is used as the discharge side electrode and a plate-shaped electrode is used as the ground side electrode, wide-ranging sterilization of sterilization objects interposed between the aforementioned electrodes cannot be achieved, resulting in uneven sterilization. If a large number of needle-shaped electrodes which are disposed with a predetermined distance apart from one another are used, a uniform discharge occurs and wade-ranging and uniform sterilization of sterilization objects interposed between the electrodes can be thereby achieved. Thus, uneven sterilization does not occur.
In order to prevent rusting and to provide durability, the needle-shaped electrode may be preferably made of a material such as a stainless material, a platinum material, or the like. Preferably, the tip of the stainless needle-shaped electrode may have a thickne
Aman Homare
Hasegawa Hideo
Takeda Koji
Tamura Toshiyuki
Conley Sean E.
Sanyo Electric Co,. Ltd.
Warden, Sr. Robert J.
Weingarten Schurgin, Gagnebin & Lebovici LLP
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