High-pressure steam sterilization

In comparison to high-pressure steam sterilization, dry heat is relatively inefficient and is usually reserved for sterilizing (or drying previously autoclaved) glassware. In the absence of superheated water, organic materials take longer to be inactivated even at much higher operational tempera-... 

The most widely used sterilization method ia the food industry is moist heat. The heat is usually suppHed by high pressure steam, but because most foods already contain moisture the role of steam is to heat the food to the required temperature. The cooking and sterilization processes can frequendy be combined into one. The food may be sealed into impervious containers of glass, metal, or plastic film and undergo terminal sterilization, or it may be presterilized in batches or in a continuous operation and then filled into a presterilized container. The latter process is called sterile filling. 

UHT milk differs from pasteurized milk mainly in the heat treatment employed for sterilization. Usually UHT milk is heated at 130° to 150°C for 2 to 8 seconds and is then aseptically packaged. In the final heating stage, steam is injected directly into the milk, or the milk is infused into a steam chamber, followed by flash evaporation to remove added water (steam). An alternative procedure, the indirect method, involves heating milk across a stainless steel barrier, using high-pressure steam as the heating medium (Mehta 1980). 

Autoclave sterilization is one of the most difficult common sterilization environments for a medical adhesive, and it is commonly used in hospitals and health care facilities for reusable devices. Autoclaves sterilize with high-pressure steam. Temperatures inside the sterilization chamber typically can reach 130°C with pressures above ambient. Certain adhesive systems, such as polyurethanes, may show hydrolytic degradation in such environments especially after multiple cycles. Epoxies perform the best under multiple autoclave exposures. However, on certain substrates, light-cured acrylics and cyanoacrylates will also perform fairly well. 

All flasks, solutions and other accessories that come into contact with the media solutions must be sterilized or purchased pre-sterilized. For sterilization, a high pressure steam autoclave (AMSCO 3021) was used with a liquid cycle that holds the contents at a temperature of 121°C/14 psi for 25 min. 

When carrying out cell disruption operations it is often necessary to provide cooling of the cell concentrate due to the high pressures developed in the equipment. An additional consequence of high-pressure operation is that cell disruption equipment can generate aerosols which may be undesirable, particularly for biologically hazardous organisms. In these cases, the ability to steam sterilize the equipment is required, for decontamination, and some type of secondary containment may also be required, such as an isolator or a contained area within a facility to which access is controlled. 

Heating of radioactive solutions, particularly under elevated pressure (e.g., steam sterilization), is also a matter of safety. In order to avoid any contaminated air to escape if a container or a seal is broken, autoclaves used for radioactive solutions should be placed inside negative-pressure sealed units. Autoclaves used for sterilizing high-energy y-emitting radiopharmaceuticals should in addition be supplied with proper lead shielding. 

One of the most important performance criteria for medical applications is that of autoclaving. This is a common method to sterilize instruments and devices that uses a combination of high pressure and steam. In an aggressive cyclic environment such as this, retention of impact properties and optical properties is important. Another essential sterilization technology that is less severe than autoclaving is the use of ethylene oxide, against which blends and alloys must display chemical resistance. 

Steam. Steam treatment of llgnocelluloses under high pressure (27-30) Is now becoming an Important pretreatment to make the substrate easily accessible to hydrolytic enzymes (31-33). The substrate Is also sterilized, and changed Into a fibrous form. A fibrous substrate Is better than the powdered form for SSF. 

Steam sterilization (autoclaving) is performed under high steam pressure at relatively low temperature (125-130°C). However, if the polymer is subjected to attack by water vapor, this method cannot be employed. PVC, polyacetals, PE (low-density variety), and polyamides belong to this category. 

Autoclaves provide steam sterilization using a combination of temperature and pressure for a set time. While autoclaving does sterilize products, it does not clean the product, so take measure to clean lab ware to remove any soil or debris. Use a manual cleaner, ultrasonic cleaner, or laboratory washer. Because of the high temperature required for autoclaving, some plastics cannot survive autoclaving due to heat requirements. These would include polyethylene, polystyrene, or polyurethane. It is important for anyone to use high-temperature sterilization processes to determine if their lab ware can tolerate high-heat applications. 

Autoclave An instrument used to sterilize items by subjecting them to steam and high pressure. 

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