lecture 22 Flashcards
(20 cards)
Can you have degrees of sterilization?
No because sterilization is either sterile or not.
What is the difference of sterilization and sanitation?
Sterilization: the destruction of all living microbes, spores, and viruses
- contaminated when exposed to air and surroundings.
Sanitation: reduces the number of pathogens or discourages their growth.
how does dry heat and moist heat different?
Dry heat requires long periods of exposure to high temperatures.
Moist heat (like boiling water) is faster and more effective at a lower temperature at a lower temperature than dry heat
Moist heat, penetrating?
More penetration, due to water widely used good filler of microbes
how is a prevaccum autoclave different than regular autoclave?
Pre-vacuum autoclave decreases cycle time and exposure of sensitive materials to steam.
-> air pulled out initially and replaced with pressurized stream.
why is fractional sterilization used? how did it work?
fractional sterilization was used at 100 degrees C for 30 minutes for 3 consecutive days, and then held at room temp. for the rest of the day.
To sterilize items, particularly food and media containing sensitive ingredients.
Why would one do a spore test? How does it work?
What does Pasteurization do? Are things Sterile? Who invented it?
Pasteurization destroys harmful microorganisms without major change in the chemistry of the food.
Does not achieve sterility.
Louis Pasteur
what are the three different versions of pasteurization? What’s good for paper containers? What does milks go through?
High Temp. Short Time (HTST)- flash pasteurization: milk
Low Temp. Long Time (LTLT)- holding or bulk pasteurizations
Ultra High Temp. (UHT): Paper containers
What is ultraviolet light doing? does it work against and what it doesn’t work aganist?
UV light can be used to control microbial growth.
Damages DNA and protiens
Good against viruses
Is x-rays and gamma better or worse then UV? what is it doing? how does it treat food?
x-rays and gamma rays (iodizing radiation) force electrons out of microbial molecules.
Not effective penetrating food.
How does a microwave work?
Long wavelengths, matches energy levels in water, water passes energy off.
Radiation us used to control microbes in food.
What does filtration do to microorganisms?
filtrations traps microorganisms.
Bactericide
Bacteriostatic
Bacteriolytic
Bacteri(cide)- killing bacteria
Bacteri(ostatic)- growth inhibiting of bacteria
Bacteri(olytic)- lysing of bacteria
What are some important properties of chemical agents in order to be good antiseptics/disinfectants
antiseptics (on the body)
disinfectants (on surfaces)
kill or slow growth of microbes
non-toxic to humans and animals
soluble in water
storable
effective quickly and at low concentrations
temp.
pH.
duration of disinfection
What is phenol coefficient (PC)? Better or worse?
PC indicates disinfecting ability compared to that of phenol
what is minimum inhibitory concentration (MIC)? how does one determine it?
MIC is the smallest amount of an agent needed to inhibit the growth of a microorganism.
Zone of inhibition: area of no growth around dics.
How do you set up a disk diffusion?
Uses solid media.
Antimicrobial agent added to filter paper dics.
Mic is reached at some distance.
