FINAL EXAM P4 Flashcards
prions
essentially infectious proteins
don’t have a nucleus
every brain has them, but we do not know their function
are shape shifters
altered prions
have destructive potential
can trigger others into an irreversible chain reaction
as this spreads, holes appear and death is inevitable
fatal familial insomnia
mad cow diesase
in England, they took waste products from sheep and fed it to the cow, transmitting the disease. by the time they realized, people had already consumed the beef, leading to the variant C J disease. humans that donated blood further transmitted the disease
Creutzfeldt-Jakob disease
genetic inherited form of cow disease
variant is what people get from consuming beef
kuru
has only been found in pacific populations, transmitted because they eat the elderly when they die
perishable food
fruits, veggies, meat, and fish
semi-perishable food
can be stored for weeks or months, doesn’t necessarily need refridgeration
stable or non perishable food
can be put on a shelf at room temp for months or years without worrying about microbes
microbial growth
can lead to spoilage or food preservation / flavor change via fermentation
effect of storage temperature
way to inhibit microbial growth
refrigerator is about 4C and dramatically slows growth
some organisms are psychrophilic and are still able to grow
freezer is about -20C and completely stops growth
acidity
aka pickling
often the result of fermentation of the food
done with vinegar (acetic acid)
are not harmful
decreased water activity
lowers or makes water less available by adding high concentrations of solute (salt or sugar)
drying also removes water
chemical preservatives
can be added and non toxic to humans
broken down in the stomach, so you’re safe
canning
form of sterilization
kills every microbial cell so food can be preserved for storage. heating time is required to kill bacterial spores
what happens if you don’t kill everything in the can
normal cans should be slightly bowed inwards
if the lid pops up and down, it was not properly prepared.
with significant growth, the microbes produce gas and buckle the can out
irradiation
the food is passed by a source of radiation. it is not radioactive, its energy simply goes through the food and peels the bacteria.
does not sterilize the food
decreases viable counts
pasteurization
heating at a moderate temperature for a short time
goal is to kill microbes without destroying food quality
decreases viable count and does not sterilize
fermented food
increases shelf life
sugars are converted to alcohol or acid (vinegar)
antibiotics are some fermentation products that are inhibitory to other organisms
produces flavor in cheese, buttermilk, yogurt, and alcoholic beverages, as well as sausages/pepperoni, cabbage (sauerkraut), cucumbers (pickles), and soy beans (soy sauce)
food poisoning
aka food intoxication
food contains a microbe, but the microbe grows in the food and produces a toxin that you eat. often “self-limiting”, you have symptoms for a short period of time and they go away.
self limiting
the amount of time for the toxin to move through your body until you feel better
food infection
infection is when the microbe has to grow inside the host
you eat the microbes on the food and it grows inside you
doesn’t take up long term residence
may or may not be self limiting
can last for weeks or months
endotoxin
lipopolysaccharide that is generally not a food poisoning toxin
exotoxin
proteins released by the microbe
enterotoxins
only affect the GI tract
