Week 2

Question 1

What do bacteria need to grow?

Answer 1

Food - carb/protein
Acidity - 4.6-7.5
Temp - TDZ
Time - to reach MID
Oxygen
Moisture

Question 2

Bacteria identified as … like what temps?
Psychrotrophic, Mesophilic, Thermophilic

Answer 2

P - Cold
M - Medium
H - Heat

Question 3

Aerobic vs Anaerobic

Answer 3

Aerobic - requires oxygen
Anaerobic - grows w/out oxygen

Question 4

Facultative anaerobic

Answer 4

Can live with or without oxygen

Question 5

Microaerophilic

Answer 5

requires a reduced amount of oxygen

Question 6

What water activity do bacteria most often grow in?

Answer 6

≥ 0.85

Question 7

Three ways to control bacterial growth

Answer 7

Manipulate environment - pH or temp
Use of chemicals
Food preservation techniques

Question 8

How are microorganisms nomenclature written?

Answer 8

Genus then species

Question 9

Main non-spore formers

Answer 9

Salmonella spp
E. coli
Listeria monocytogenes
Staphylococcus aureus
Campylobacter spp

Question 10

Main spore formers

Answer 10

Bacillus cereus
Clostridium botulinum
Clostridium perfringens

Question 11

What are biofilms?

Answer 11

microbial aggregations that attach to the surfaces of living or nonliving things
provide protection for microorganisms

Question 12

Differentiate between yeasts and molds

Answer 12

molds - larger, reproduce by spores, require oxygen
yeasts - smaller, liquids with sugar or acid

neither are heat resistant

Question 13

Aflatoxin

Answer 13

mycotoxin produced by mold posing the greatest threat to health

Question 14

Viruses

Answer 14

leading cause of food borne illness in the US
can only replicate in a living host

Hep A and Norovirus are of the most concern

Question 15

Two key properties of food that influence shelf life

Answer 15

Water activity and pH

Question 16

Water activity calculation

Answer 16

vapor pressure of water in a material/vapor pressure of pure water at the same temp.

equilibrium relative humidity(%)/100