Ch17 Flashcards
perishable foods
semi perishable foods
non-perishable foods (give ex. of all)
food that easily supports the growth of microorganisms (raw meat/ green salad)
food that does not spoil as easily (nuts/ potatoes)
food that prevents the growth of microbes because that lack water (flour/sugar/ dried beans)
What causes food to spoil?
growth of bacteria in food
The likelihood of food spoiling depends on:
Intrinsic factors (the characteristics of the food itself)
Extrinsic factors (the way the food is stored)
Why are refrigerators used to store foods
They slow the growth of pathogens that grow better in room temperatures
Is dry or moist food more perishable? Why?
Moist foods; the water content
What is water activity? What is the water activity of fresh foods? What water activity do most spoilage bacteria require? What food have a lower water level
The amount of water accessible to microorganisms (a(↓w))
>.99 a(↓w)
.91
dry foods and foods that have a high solute content (like sugar/salt)
enterotoxins
What water level can the microbe that makes this thrive?
secreted by S. aureus; act on the intestine causing foodborne illnesses
.86 (a(↓w))
State the typical spoilage patterns of:
fruits/vegetables
fresh meat/ poultry/ seafood
milk
pectin being hydrolyzed
sugars being fermented
proteins undergoing proteolysis/deamination
carbohydrates being hydrolyzed
lactose being hydrolyzed/ fermented
proteins (casein) undergoing proteolysis/deamination
Is mold spoilage more common in vegetables or fruits? Why?
Fruits, since it is more acidic
What phases of microbial growth determine food spoilage?
What methods are done to prevent food spoilage?
lag phase @ beginning as well as the exponential phase
EXTENDING lag phase/ reducing microbial growth
changing pH
storage temperature
What can be done to prevent food spoilage?
drying meat/ fruit in sun
SMOKING meat
adding high amounts of salt/sugar
heating/ refrigeration
lyophilization
freeze-drying; food is frozen & dried under a vacuum
What are bacteria that can tolerate refrigerator temperatures described as? (give an ex.)
psychrotolerant; Listeria (L.) monocytogenes
What did Nicolas Appert do?
responsible for canning (food sealed inside a jar was heated in boiling water for hours, undergoing HIGH HEAT processing)
botulism
What was done as a solution for this?
disease caused by Clostridium bacterium
associated with contamination of food in early canning procedures
D value (time required to kill 90% of target organisms was studied)
pasteurization
heat processing/ partial sterilization of the food product
(heating/irradiating/ applying high pressure)
not high heat processing like canning
pickling
irradiation
bacteriocins
process of lowering PH of a food by storing/ marinating in chemicals like vinegar
exposing food to radiation
products releases by microbes to kill other microbes
modified atmosphere packaging
(MAP) vacuum packaging, the atmosphere around food is altered to extend shelf life
What technology is implemented when modified atmosphere packaging when microbes like C. botulinum can thrive in these environments?
(describe it)
(give an example)
hurdle technology; constraints that the microbe must overcome to thrive; changing pH levels/ water availability/changing gas concentrations, etc.
starter cultures
microorganisms added to frood to help in the production of FERMENTED products
BRIEFLY describe milk/vegetable/meatfermentation
lactic acid bacteria (LAB) is prevalent in food fermentation like yogurt, kefir, cheese, sauerkraut, etc.
Briefly go through the steps from milk to yogurt
- start with milk
- adjust fat content
- pasteurization
- adding starter cultures
- ferment as lactose sugars change into lactic acid
- add fruit/ sweeteners
Why are starter cultures usually mixed?
Natural microbes are, not always reliable, so microorganisms with intended strains are added
rennin
protease/enzyme that results in the curding of milk
(addition with whey results in cheese)
For blue cheese, what microorganism is responsible for that mold (blue vein) appearance
Penicillium ROQUEFORTII
Describe vinegar
dilute acetic acid; the result of wine souring; good as a preservative by managing pH; associated with acetobacter
Briefly describe the Trickle/quick method o bacteria
ethanol-containing liquid on a bed of wood twigs
as it passes through the bed, the ethanol is metabolized into acetic acid by the biofilm of acetic acid bacteria
common source outbreaks
outbreaks of foodborne or waterborne illnesses
Salmonellosis
common foodborne disease found in the GI tract of chickens; can contaminate eggs/ meat
ORT
Oral rehydration therapy; increases fluid intake by mouth to fight symptoms caused by enterotoxins like (dehydration/ diarrhea
foodborne intoxication
foodborne infection
illness caused by ingestion of microbial exotoxins SECRETED (by microbes like S. aureus)
illness caused by the ingestion of ORGANISMS themselves
How are these toxins destroyed?
How do people get them?
food thoroughly cooked/heated usually destroy toxins
many foods that come in contact with microbes that secrete the toxins are served warm or cold
What does it mean when water is potable
It is drinkable; free from intestinal bacteria/pathogens
What percentage of the water on our planet sustains us?
3% (freshwater), other 97% is saltwater; aquifers also help
What are methods implemented to keep water safe
wastewater treatment (reduction of TOC (total organic carbon), removal/inactivation of microbes, reduction of inorganic nutrients prior to the EFFLUENT (outflow) to lake/stream
persistent organic pollutant
(POP) chemicals that are difficult to break down in wastewater treatment plants
\may affect the reproduction/development of fishies
Describe the steps of wastewater movement through an effective treatment plant
Pretreatment (removal of large objects)
Primary Treatment (removal by sedimentation (of matter)/ skimming (of oil))
Secondary Treatment (trickling filter/activated sludge; microorganisms that break down waste)
Disinfection (chlorination/ ozonation/UV)
Tertiary Treatment (rare)
what is the biochemical oxygen demand
the amount of dissolved oxygen required to decompose organic matter in sewage/ water
indicator organisms
fecal coliforms
most probable number
microorganisms that indicate the presence of fecal matter /pathogens
MPN (most probable number) tests for coliform #s in water
a type of indicator organism in the intestinal tract of humans
What are the products of:
HOMOlactic fermentation
HETEROlactic fermentation
ETHANOLic fermentation
What pathway do each go through?
lactic acid only
product is ethanol, lactic acid and CO2
ethanol and CO2
EMP glycolytic pathway
Saccharomyces cerevisiae
the sugar fungus, different strains result in different products
Describe the steps of beer making
malting (starch is turned into sugars)
milling, mashing (sugar extraction)
wort boiling (boiling and sterilization to get wort)
fermentation (sugars converted to ethanol/ carbon dioxide)
post-fermentation improving flavor/ maturation)
barley
hops
adjuncts
the top fermenters make what
the bottom fermenters make what
grass used in beer brewing
herbs used to flavor beers
extra starch source used to flavor beers
ale
lager
What are the differences between white and red wine?
red wine ferments with skin
white wine ferments for about 2 weeks and then ages for 5 months
red wine ferments for 3 weeks and ages for 2 years in barrels, the another 6 months in bottles
