Physical Sterilants

Hot water ( 82°G/180°F) or steam is an ideal sterilant. It has penetrative properties, works against all wine/juice microorganisms, is noncorrosive, and relatively inexpensive. Bottling line sterilization can be accomplished with steam or hot water. Where hot water is employed to sanitize lines, recommend minimal temperature X time requirements are 82° G (180°F) for more than 20 min. When steam is used to sterilize tanks, the recommendation is to continue until condensate from valves reaches 82° G for 20 min. In both cases, the temperature should be monitored at the furthest point from the steam source (i.e., the end of the line, fill spouts, etc.). The practice of dismantling valves, racking arms, and so on and immersion in containers of hot water may not yield the time and temperature relationships necessary for sanitization. 

Ultraviolet (UV) light is directly effective against microbes. Unfortunately, it has low penetrative capabilities and even a thin film will serve as an effective barrier between radiation and microbes. Thus, its use is generally restricted to laboratory applications for surface sterilization. Skin and eyes must be shielded (by glass) from continued exposure to UV light. Ozone (O3) is being used in water treatment. Ozone degrades rapidly in warm water ( 35°G/95°F). Thus, at present, its primary application is cold-water recirculation systems. 

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Brewer, J.H. Sterility tests and methods for assuring sterility. In Antiseptics, Disinfectants, Fungicides and Chemical and Physical Sterilization Reddish, G.F., Ed. Henry Kimpton London, NC, 1957. 

PB Price. In GF Reddish, ed. Antiseptics, Disinfectants, Eungicides and Chemical and Physical Sterilization. 2nd ed. Philadelphia Lea and Eebiger, 1957, p. 399. 

Management of LAB and MLF can go astray at any juncture in the winemaking process. The following section addresses the chemical and physical manifestations of mismanagement. Use of preservatives or chem-ical/physical sterilization will be considered along with bottling in Chapter 6. 

If physical sterilization procedures cannot be applied, e.g., because a contamination source is located inside a machine or a production cannot be run under sterile conditions due to cost reasons, several chemical measures are available for the reduction... 

Hospital sterilizer loads vary in composition, thus the challenge presented to the test organism can vary considerably, depending on the type and contents of packages in which they are placed. The benefits of a standardized test-pack constmction and test protocol are obvious, and such recommendation is made by AAMI for steam and ethylene oxide sterilizers (11). More recentiy in European (CEN) and International (ISO) standards, biological indicators are considered as additional information supplemental to the measurement of physical parameters. Indeed, for sterilization using moist heat (steam), the biological indicator information is not considered to be relevant. 

The choice of a particular mining method depends on a number of parameters, typically the physical properties of the host matrix, the fiber content of the ore, the amount of sterile materials, the presence of contaminants, and the extent of potential fiber degradation during the various mining operations (33). However, most of the asbestos mining operations are of the open pit type, using bench drilling techniques. 

Sterilant is a chemical or physical agent that destroys all forms of microbial life. 

Table 7-14 Example of mechanical and physical properties of plastics after sterilization... 

Published by the Plastics Design Library, PDLCOM is an exhaustive reference source of how exposure environments influence the physical characteristics of plastics. Data include resistance to thousands of chemicals, weathering and UV exposure (i.e. color change after accelerated weathering or outdoor exposure) sterilization (radiation, ethylene oxide, steam, etc.) thermal air and water aging environmental stress cracking and much more. 

At first, the program which investigated the packaging of irradiation-- processed foods, concentrated on the most advanced type of container, the tinplate can. It had performed successfully for a century as a container for thermoprocessed foods. However, as a container for the irradiation-processed foods, its physical, chemical, and protective characteristics had to be evaluated, including the effects of radiation on enamels and end-sealing compounds. This container was satisfactory for packaging foods that were irradiation sterilized while unfrozen (1, 2). 

Laboratory cabinets are available in both wood and steel. Educational laboratories often use wood, while industrial laboratories usually prefer steel. Wood cabinets do not have the sterile look of steel, but they are far less resistant to physical abuse. They come prefinished with a wood stain. A damaged area is not difficult to refinish. Wood cabinets have no rust problems, but some users have complained about poor chemical resistance of the interiors. The quiet operation of doors and drawers with no metallic noises is appreciated by many. 

Bacterial spores are the most resistant of all microbial forms to chemical treatment. The majority of antimicrobial agents have no useful sporicidal action, with the exception of the aldehydes, halogens and peroxygen compounds. Such chemicals are sometimes used as an alternative to physical methods for sterilization ofheat sensitive equipment. In these circumstances, correct usage of the agent is of paramount importance since safety margins are lower in comparison with physical methods of sterilization (Chapter 20). 

All disinfection and sterilization processes for equipment should be validated, for preference using a microbiological challenge with an organism of appropriate resistance to the disinfectant, sterilant or sterilizing conditions. Once the required log reduction of the challenge organism has been achieved, physical and/or chemical parameters can be set which form the critical control points for the process. 

Steam for sterilization can either be generated within the sterilizer, as with portable bench or instrument and utensil sterilizers, in which case it is constantly in contact with water and is known as wef steam, or can be supplied underpressure (350-400kPa) from a separate boiler as dry saturated steam with no entrained water droplets. The killing potential of wef steam is the same as that of dry saturated steam at the same temperature, but it is more likely to soak a porous load creating physical difficulties for further steam penetration. Thus, major industrial and hospital sterilizers are usually supplied with dry saturated steam and attention is paid to the removal of entrained water droplets within the supply line to prevent introduction of a water fog into the sterilizer. 

Principles of the methods employed to sterilize pharmaceutical products are described in Chapter 20. The British Pharmacopoeia (1993) recommends autoclaving and filtration as suitable methods applicable to aqueous liquids, and dry heat for non-aqueous and dry sohd preparatiorrs. The choice is determined largely by the ability of the formulation and container to withstand the physical stresses apphed by moist heat... 

This is an insoluble gelatin foam produced by whisking warm gelatin solution to a uniform foam, wtiieh is then dried. It ean be cut into suitable shapes, paeked in metal or paper containers and sterilized by dry heat (150°C for 1 hour). Moist heat destroys the physical properties of the material. Immediately before use, it ean be moistened with normal saline eontaining thrombin. It behaves as a meehanieal haemostat providing the ftamewoik on wtiieh blood elotting ean oeeur. 

Monitoring of the sterilization process canbe achieved by the rrse of physical, chemical or biological indicators of sterilizer performance. Such indicators are frequently employed in combination. 

GC Na, HJ Stevens, BO Yuan, N Rajagopalan. Physical stability of ethyl diatrizoate nanocrystalline suspension in steam sterilization. Pharm Res 16(4) 569-574, 1999. 

Aseptic Crystallization and Dry Powder Filling. Aseptic crystallization is primarily used for manufacture of sterile aqueous suspensions. However, if the physical form of the drug is critical to quality of the final product, better control over physical form can be attained by aseptic crystallization because a large variety of organic solvents can be used to control the crystallization process. In aseptic crystallization, the drug is... 

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