In: Nursing
MICROBIOLOGY: I'm having trouble understanding the role of thermal death time and thermal death point in proper sterilization. Can someone please explain the role of both in proper sterilization?
Sterilisation
It is the process that remove,kill or deactivates all forms of life including fungi,bacteria,viruses
Thermal death time is how long it takes to kill a specific bacterium at a specific temperature.it was originally developed for food canning and has found applications in cosmetics producing salmonella free feeds for animals and pharmacueticals
Most of organism death time is 10 mnt.
Heat : kills microrganism by denaturating their enzymes and other protiens.Heat resistance varies widely among microbes.
Thermal death time can be determined one of the 2 ways
1) by using graphs
2) by using mathematical formulas
Graphical method
This is usually expressed in minutes at the temp. Of 250 degree faranheat (121 °c).this is designated us ' f0' .Each 18°F or 10 °C change results in a time change by factor of 10.This would be shown either as f10 121 =10 minutes( celcius) or f18 250 = 10 mnt ( faranheat )
Formula method
This was plotted on semilogarithmic paper though it can also be done of spreadsheet programs.
Time shown as x axis and temp.shown in y axis.
The simple heating curve can also determine lag factor (j) and slop (Fh).It also measures the product temp.rather than the can temp.
Thermal death point
Lowes temp.at which all of the microbes is a liquid suspension will be killed in 10 mnts