What Is a Sterilizer?
A sterilizer is a device that can sterilize food and other objects. Sterilizers can be broadly classified into ultraviolet (UV) sterilizers and high-temperature, high-pressure sterilizers.
UV sterilizer, which uses ultraviolet light for sterilization, has the advantage of causing little damage to the object and preventing the development of resistant bacteria. However, since it can only sterilize the surface where the ultraviolet rays hit, it is not effective enough if something blocks the ultraviolet rays.
High-temperature, high-pressure sterilizers heat and sterilize food under high-temperature, high-pressure conditions to shorten the time required for sterilization. Unlike autoclaves, which are a similar type of sterilizer, this device has a cooling function, effectively minimizing the cooling duration.
Uses of Sterilizers
Sterilizers are used for the purpose of hygiene control and contamination prevention. They are used in a wide range of fields, including chemicals, pharmaceuticals, and precision products. They are especially indispensable in the food industry, where contamination by harmful bacteria is not permitted.
Typical applications in the food industry include sterilization of retort pouch foods, such as canned and bottled foods. In vacuumed foods such as canned and bottled foods, “botulism,” a bacterium that hates oxygen, can easily multiply.
Botulinum is a well-known toxin-producing bacterium that can cause food poisoning, so careful sterilization using sterilizers is necessary when manufacturing the above foods.
Principle of Sterilizers
There are two main types of sterilizers: high-temperature, high-pressure sterilizers and ultraviolet sterilizers.
High-temperature, high-pressure sterilizers, are used to sterilize harmful bacteria, including botulism, contained in food products. Botulism is known to protect itself by forming heat-resistant “spores,” and must be sterilized by heating to a sufficient temperature and time. Food safety can be maintained by using high-temperature, high-pressure sterilizers to sterilize food under strict conditions equivalent to 120°C for 4 minutes.
There are two types of high-pressure sterilizers: steam type and hot water type. The hot water type is further divided into hot water storage type and hot water spray type. In the hot water spray type, hot water is sprayed to create a high-temperature, high-pressure atmosphere in the sterilization tank, thus preventing uneven temperatures.
The second type of sterilizer is the ultraviolet sterilizer, which irradiates the object with ultraviolet rays. Irradiation with ultraviolet light can destroy the cell membranes of bacteria, resulting in their death.
Mercury and ozone lamps are the main sources of ultraviolet light used in sterilizers. By employing these lamps, it is possible to irradiate ultraviolet rays with a wavelength (UV-C region) that is easily absorbed by cell membranes and has good sterilization efficiency.