Sterilization technologies

It is an axiom of sterilization technology that appropriate conditions must be estabUshed throughout the material to be sterilized. The time-at-temperature conditions are critical when considering any sterilization method using heat. 

Orth has applied the concepts of the D-value as used in sterilization technology (Chapter 20) to the interpretation of challenge testing. E q)iessing of the rate of microbial inactivation in a preserved system in terms of a D-value enables estimation of the nominal time to aehieve a prescribed proportionate level of kill. Problems arise when trying to prediet the behaviour of very low levels of survivors, and the method has its detractors as well as its advocates. 

Haseley, P. New cooling and sterilization technology in freeze-dryers and a comparisation of operating costs. PDA Aisan Symposium, p. 305-317, Tokyo 1994... 

Owens, J. Sterilization of LVPs and SVPs. In Sterilization Technology A Practical Guide for the Manufacturer s and Users of Health Care Products. Morrissey, R.F., Philips, G.B. (eds.) New York Van Nostrand Rheinhold, 1993. 

Phillips, G. B., and Morrissey, R. F. (1993), Sterilization Technology A Practical Guide for Manufacturers and Users of Health Care Products, Van Nostrand Reinhold, New York. 

Akers, J. Agalloco, J. Aseptic processing—a current perspective. In Sterilization Technology Morrissey, R., Phillips, G.B., Eds. Van Nostrand Reinhold New York, 1993. 

Another possibility, proposed by Rodriguez et considers the concept of accumulated lethality (Fo), used for thermal sterilization, but applied to optimization of EtO sterilization technology. A mathematical model of the inactivation of biological indicators spores by EtO was developed, along with two formulas a response equation for calculating the number of survivors of a sterilization cycle, and a formula for determining the accumulated lethality of exposure to EtO. Experiments verified that the equations are applicable to processes with relative humidity values between 15% and 90%, enabling users to compare the lethality of dissimilar EtO cycles. 

Pistolesi, D. Mascherpa, V. Moist and Dry Heat Sterilization Technology Fedegari Autoclavi S.p.A. Albuzzano, PV, 1999 CD-ROM. 

---