PRELAB 1 Extrincsic fastors

Question 1

Extrinsic factors what is it

Answer 1

condition of storage

Question 2

What are the extrinsic factors

Answer 2

temperature
relative humidity
environmental gases
presence of other microorganisms

Question 3

Pyschrotrops
grows well ____
optimum _____
causes _____
e.g.

Answer 3

<7
20-30
food spoilage
Pseudomonas, enterococcus

Question 4

Mesophiles
grows well at ____
optimum ____
mostly ______
e.g

Answer 4

20-45
30-40
food-borne bacteria
Streptococcus pyrogenes, Listeria monocytogenes

Question 5

Thermophiles
grows well at ______
optimum _____
e.g

Answer 5

> 45
55-65
Bacillus Clostridium

Question 6

survive but do not grow well or reproduce at lower temp

Answer 6

Psychroduric

Question 7

Survive but do not grow well at high temp
example

Answer 7

thermoduric
Corynebacterium - survive past pasteurization

Question 8

Relative humidity

Answer 8

can change Aw

Question 9

Environmental gases

Answer 9

O2
CO2
Ozone

Question 10

presence of other microorganisms

Answer 10

some foodborne organisms produce substances that can be inhibitory to other organisms such as acids and enzymes

Question 11

examples of competitive exclusion

Answer 11

general microbial antagonism
lactic antagonism