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184 Cards in this Set

  • Front
  • Back
Microbial contamination
absence of significant contamination
prevents contamination of culture, personnel, and the environment
antiseptic technique
Eliminating ALL microbial life EVEN virus
Is commercial sterilization real sterilization
Commercial sterilization
used for processing canned food

kills everything except thermophilic spores
Can thermophilic spores germinate at ambient temperature
Can thermophilic spores survive commercial sterilization
What should you store canned foods at
under 40 degrees C
eliminating vegetative pathogens
What is the purpose of disinfection
to reduce the risk of infection or spoilage
What is antisepsis
eliminating vegetative pathogens from living tissues
What is the difference between disinfection and antisepsis
different uses: one is on surfaces; one on tissues
What is disinfection plus cleaning
What is the purpose of sanitization
eliminate pathogens, organic debris, dirt
What is microbicide?
kills mos
What is germicide
kills germs
What do microbicide/germicide do?
kill microbes
What is inhibiting but not killing microbes
What is microbial death rate
log rate death: drop by one log
What does the effectiveness of antimicrobial treatment depend on?
number of microbes, exposture time, susceptibility of the microbe, environmental conditions, and concentration/dose of the agent
What is very resistant to drying and chemical treatments
mycobacterium/ waxy layer
What is very resistant to all treatments
spores/ multiple layers
Why are G- more resistant
outer membrane with selective permeability
What are some environmental conditions that affect antimicrobial treatment
temperature, pH, moisture, organic substances
What does a higher temp generally do
speed up reaction
What are some organic substances that protect mos
sugar, fat, polysaccharide
What does chlorine work best in
acidic pH
In acidic env't, mos can be killed...
with a lower temperature
What is the only exception to the fact that antimicrobial effect increases with the concentration or dosage
What must alcohol be used with
What do microbial control agents do?
alternation of membrane permeability, damage to proteins, damage to nucleic acids
What is the time to kill all cells in a culture with heat
thermal death time
What is the lowest temperature at which all cells in a culture are killed in 10 minutes
thermal death point
What is the minutes it takes to kill 90% of a population at a given temperature
decimal reduction time
What is the commonly used time?
decimal reduction time
What does a longer TDT (thermal death time) mean?
harder and more resistant
What is the most commonly used method?
What does moist heat do?
denature proteins
What is steam under pressure
What are some examples of moist heat
boiling, autoclave
in order to heat water above 100 degrees C at sea level, what must you do?
use pressure
The higher the pressure...
the higher the boiling point
What are some things you should not autoclave?
heat sensitive, flour, milk powder, vitamins, antibiotics, water insoluble substnaces
What will a larger volume mean for autoclaving?
longer to penetrate
What is the protein that causes mad cow disease
What degrees is boiling
100 degrees
Can you use boiling for sterilization
no, cannot kill endospores
Does boiling kill vegetative cells
Does boiling kill viruses
Does boiling kill endospores
Does boiling kill mold spores
What is a mild heat treatment used to reduce spoilage organisms and pathogens
What are some things that are pasteurized
milk, OJ, cheese, sauerkraut
What are the types of pasteurization
low temp holding, high temp short time, ultra high temp
what is low temp holding?
use a low temp about 63 degrees celsius for 30 minutes
What is high temp short time
72 degrees C for 15 seconds
What is ultra high temp?
140 degrees celsius for less than one second
What can destroy milk over time
What organisms survive pasteurization
What is special about ultra high temperature
can be shelf stored because it kills spoilage pathogens
How does dry heat kill
Does dry heat penetrate
What requires a higher temp and longer exposure due to slow penetration
dry heat
What are some examples of dry heat?
flaming, incineration, hot air sterilization
What is the oven equivalent to dry heat
hot air oven 170 degrees C for 2 hours
What is the autoclave equivalent of dry heat
121 degrees C for 15 minutes
low temperature
cannot control microbial growth but cannot be used to destroy mos and preserves microbial culture
Most what wont grow during refrigeration
What grow slowly in refrigeration
What occurs at a lower temp
slower growth rate
What occurs if the temp is really low
wont grow
Can mos grow w/o water
Why can cells not grow if frozen
if the water in the cell is frozen, it won't have water for growth
What is slow freezing
-20 degrees C for several hours
What is fast freezing
-70 degrees C within 20 minutes
What is freeze drying
freezes instantly and then dries
What is used to preserve stuff?
fast freezing
What is freezing?
below 0 degrees: not pure H20
What is freezing material rapidly first and then dry under the vacuum
freeze drying
What is freeze drying?
gently used to preserve bacterial cultures
Is low temperature used to kill mos?
What type of mos will grow at refrigeration temperatures?
Will mos grow at freezing temperatures?
Which of the following types of freezing is more harmful to microbes?
slow freezing
What is removing water to stop microbial growth?
What does dessication do?
prevents metabolism
What is drying used for?
food preservation
What survives drying?
most mos but not all: spores survive well
What causes plasmolysis?
high osmotic pressure
What is plasmolysis?
cell shriking
Why do we use salt and sugar to preserve food?
create a high osmotic pressure (hypertonic env't) in which mos lose H20 and can't grow
What grows in a high salty env't?
What does radiation do?
damage DNA
What are types of ionizing radiation
x rays, gamma rays, electron beams
What is non ionizing radiation?
How do microwaves kills mos?
by heat, not by radiation
How does a microwave generate heat?
by friction
What does UV radiation do?
make T-T dimers
What can become sterile without heat
gamma rays
What is the only type of radiation that kills microbes
What does ionizing radiation do
break DNA, irradiated H2O generates free radicals to damage cells
Can you use ion radiation to cause sterilization?
What is the most effect wavelength to kill mos?
260 nm
What are bacteriocidal wavelengths?
200-280 nm
What is stronger bacteriocidal?
shorter wavelength
What is only effective on the surface
UV light
What is UV light
136-400 nm
What is the most effective wavelength
260 nm
What is UV absorbed by
cellular DNA and form thymine dimers that distort DNA strands
What is the major disadvantage of using UV?
poor penetration power
What does filtration do
removes microbes (particles) from liquid or air
What stays on the filter in membrane filtration?
anything larger than spores
What is an example of membrane filtration?
What should you use a hood for?
mycobacterium/ TB
What could pass through the pore size of 0.22 micrometers?
small viruses, pliable bacteria and prions
What could pass through the pore size of 0.45 micrometers?
viruses, small bacteria and prions
What does HEPA stand for?
high efficiency particulate air
What does high pressure do?
denatures proteins and damages cell structures
What can be pasteurized
What is the advantage of high pressure
doesn't use heat, heat can destroy flavor
What are factors that influence chemical controls?
concentration of disinfectant, organic matter (protect mos), pH, temperature, time
WHat does an acidic pH do?
may decrease resistance or usually an increase in temperature, you get a better result
What are the only chemicals that can kill endospores?
What are some chemosterilants?
ethylene oxide, glutaraldehyde, heated hydrogen peroxide, peracetic acid
What can treat surgical instruments?
What is the BP of ethylene oxide?
10.2 degrees C- toxic
What is the disadvantage to using ozone?
no toxic residuals because it must travel in pipes and recontaminate
What does peracetic acid do?
kills endospores within 30 minutes, kills vegetative cells within 5 minutes
How is peracetic used?
on food processing and medical equipment
What are the advantages of using peracetic acid?
no toxic residuals, not affected by organic matters
What is the application of hydrogen peroxide?
aseptic food packaging materials are sterilized with hot solution of hydrogen peroxide
What is hydrogen peroxide?
35% H2O2 and 40-80 degrees C
What is the advantage of hydrogen peroxide
no toxic residual, vaporized H2O2, high penetration
What is hydrogen peroxide used at home for
generate O2 bubbles to lift dirt
What does hydrogen peroxide break down into
water and O2
What is a phenol coefficient of 1
same as phenol
What is a phenol coefficient over 1
better than phenol
What a phenol coefficient below 1
not as good as phenol
What is phenol
toxic and irritating
What are derivatives of phenol that are less irritating
What is used nowadays?
What is the very 1st disinfectant ever used?
What will most likely not kill endospores
PAGE 280
What is effective against all bacteria, many endospores, fungi and viruses?
What is iodine in alcohol solution
tincture of iodine
What is iodine plus an organic carrier
What slowly releases iodine and is less irritating but doesn't stain?
What is not very pleasant; burns
tincture of iodines
What are some oxidizing agents that inactive enzymes
halogens, iodine, chlorine
What is used to treat water effective concentration of 0.5-1.0 ppm
What is HOCl
hypochlorous acid
How does pH influence the effectiveness of chlorine
in an acidic env't a lot of hypochlorous acid is made
What is bleach?
sodium hypochloride (NaOCL)
What is an active antimicrobial ingredient?
hypochlorous acid
What inactivates proteins by cross linking with functional groups?
How can aldehyde kill spores
probably for a high concentration for a long time
What is used for disinfection of medical equipment?
What is used for fumigation?
formaldehyde gas
What is used to disinfect a whole room?
What is formalin?
37% aqueous soluntion of formaldehyde that is used to preserve corpse, tissue, inactive viruses to prepare vaccines
What denatures proteins and dissolves lipids and can kill vegetative cells but not endospores
alcohols (ethanol, isopropanol)
What is an effective form of alcohol?
The lower the alcohol conc...?
the higher the exposure time needed
What is needed for alcohol effectivness?
What is the action of heavy metals?
oligodynamic action
What do heavy metals do?
denature proteins
What are some heavy metals?
AgNO3, CuSO4, Mercurochrome
What is a skin antiseptic
What are the functions of surface active agents or surfactants
as a wetting agent to help remove dirt and fats that protect mos, and remove mos from surface
What does soap do?
What does acid-anionic detergents do?
What can soaps do?
bind oil and water and can wash away bacteria under the oil
Can antimicrobial soap sterilize
What can quaternary ammonium compounds do?
bactericidal and disrupt the plasma membrane
What is quaternary ammonium compounds effective against?
enveloped viruses, G+, fungi but not effective against G- and endospores, some bacteria can grow IN them
What do organic acids do?
inhibit metabolism (fungi), sorbic acid, benzoic acid, calcium propionate, control molds and bacteria in foods and cosmetics
What does nitrite do?
prevents endospore germination (botulism/ clostridium botulina and carcinogens)
What do antibiotics do?
nisin and natamycin prevent spoilage of cheese
What do all meats that show a pink color have?
What is benzoine used for?
soda/inhibits yeeast
What is calcium propionate for?
on bread to inhibit mold growth
Graph in notes pg 20