Chapter 12 - Microbiology of Food & Water Flashcards
_____ ________ can reduce the amount of food we have available for consuming.
food spoilage
Food ____________ methods can make food last longer without spoiling.
preservation
What does the contamination of food and water by microbes cause?
human diseases
What foods easily support microbial growth and spoil fast (salad, fresh meat)?
perishable foods
what foods don’t spoil as quickly (nuts, potatoes)?
semi-perishable foods
what foods remain edible for long periods (flour, sugar, dried beans)?
non perishable foods
likelihood of spoilage is related to _________ (food properties) and _________ (storage environment) factors.
intrinsic, extrinsic
_________ factors:
water availability
osmolarity
nutrient content
pH and buffering capacity
antimicrobial constituents
biological structure (rinds + shells)
intrinsic
___________ factors:
temperature
humidity
presence + concentration of gases
extrinsic
What is an example of food spoilage being desirable?
milk changing to form cheese, yogurt, butter, etc.
aw=
water activity of food
reduction of water activity of food:
______ food out or by adding _______ (salt/sugar)
drying, solutes
Control of temperature:
Heat-treatment process that destroys pathogenic microorganisms in certain foods.
pastuerization
control of temperature:
Process of cooling and heating combined with pressure to eliminate endospores.
canning
Milk Pasteurization; heating at 63° C (145° F) for 30 minutes
low temperature hold (LTH)
Milk Pasteurization; heating at 72° C (161° F) for 15 seconds.
high-temperature, short-time (HTST)
Milk Pasteurization; heating at 138 to 150° C (280 to 304° F) for 2 seconds or less.
ultra-high temperatures (UHT)
- bacteriocins (nisin)
- lactic acid
- acetic acid (vinegar)
natural antimicrobial preservatives
- sodium benzoate
- propionate
- sorbates
- sulfur dioxide
- nitrites
artificial preservatives
Exposure to radiation, commonly used to reduce microbial contamination of food and surfaces.
irradiation
Irradiation that does not penetrate materials well, so its use is limited to surface sterilization.
non-ionizing radiation (UV)
stronger, more penetrating radiation used for pasteurization and sterilization of foods.
ionizing radiation (gamma and x-rays)
__________-___________ _________ (___) = vacuum packing/ taking the oxygen out.
modified-stmosphere packaging (MAP)
______ technology = combining more than one approach to food preservation.
hurdle
_______ ________ of microbes are added to food to begin the fermentation process.
starter cultures
_______ ____ _________ (___) are used to produce cheese + yogurt.
Lactic Acid Bacteria (LAB)
What form of fermentation is commonly used in Asia to produce products like Miso, tempeh, soy sauce and sake?
fermentation with mold
Vinegar is produced by the fermentation of _______ by acetic acid bacteria into _______ ____.
ethanol, acetic acid
Illness caused by ingestion of food containing microbial exotoxins.
foodborne intoxication
Disease caused by the ingestion of live pathogens that actively multiply within the body.
foodborne infection
Only about __% of the water found on Earth is freshwater.
3
_________________= an increase in the concentration of nutrient leading to rapid growth of autotrophic populations (mostly algae).
eutrophication
A goal of wastewater treatment is to reduce inorganic compounds that contain nitrogen and phosphate to prevent ________________.
eutrophication
The physical removal of large objects from water
pretreatment
the physical removal of sediments and grease that form primary sludge from water.
primary treatment
uses trickling filter + activated sludge unit to form complex biofilms that break down organic compounds over time.
secondary treatment
not always used, filtration method
tertiary treatment
chlorination, UV light exposure, or ozonation
disinfection
clumps of biomass of adsorbed material + biofilm microbes
flocs
