Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Foodborne Pathogens > Powerpoint 4: Factors that influence microbial growth > Flashcards

Powerpoint 4: Factors that influence microbial growth Flashcards

1
Q

Which parameters can be used to limit bacterial growth?

A
  • temperature
  • pH
  • redox potential
  • water activity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the most important environmental factor affecting the growth and survival of organisms?

A

Temperature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What does redox potential measure?

A

measures the potential energy difference in a system generated by a coupled reaction in which one substance is oxidized and a second is reduced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Who is the reducing agent?

A

The electron donor. It reduces the oxidizing agent.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the primary means of generating energy in microbes?

A

Oxidation and reduction of substances

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

In what state are fresh fruits and vegetables found?

A

Reduced state

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Microorganisms who can use free oxygen and bound oxygen are called?

A

Facultative anaerobes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are microorganisms who can grow better in the presence of less oxygen called?

A

Microaerophiles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is a common way to decrease microbial growth?

A

Modified atmosphere packing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the most important anaerobe in food called?

A

Clostridium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What pH can’t Clostridium grow in anymore?

A

Below pH 4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What can cause meat putrification

A

Clostridium laramie

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What can cause fatal foodborne illnesses?

A

Clostridium botulinum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is controlled atmosphere packaging (CAP)?

A

The atmosphere in a storage facility is altered and the levels of the gases are continually monitored and adjusted.

  • expensive
  • long term storage of fruits and vegetables
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is modified atmosphere packaging (MAP)?

A
  • does not require high degree cotrol
  • food is enclosed in a high gas barrier packaging material
  • air is removed, and flushed with a particular gas or combination of gases
  • package is hermetically sealed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Vacuum Packaging (VP)?

A
  • removal of air from the package

- sealing the package hermetically

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is used in the preparation of ready to eat meat?

A

vaccum packaging VP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Up to how many weeks can VP extend shelf life?

A

8 weeks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is used to extend the life of fresh pasta, bakery product, cooked egg products, and fresh seafood?

A

Gas flushing MAP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the pH range of neutrophile bacteria?

A

6-8

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the pH range of alkaliphile bacteria?

A

8-11

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the pH range of acidophiles?

A

1-4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

In general, what microorganisms grow better at low pH?

A

-yeast and molds > gram + > gram-

24
Q

Why are acids with a lower dissociation rate (weak acids) more problematic for bacteria?

A
  • undissociated molecules are lipophilic: they enter into the cell and dissociate to generate H+ in the cytoplasm, causing an increase in the the internal cellular pH
  • destroys the proton gradient and ability to generate energy.
25
Q

What is particularly important in canned food for preservation?

A

acid

26
Q

T/F: acids are used in several foods to prevent the growth of pathogens and spoilage bacteria.

A

true

27
Q

What is the acid that is used as vinegar, or sodium or calcium salts in >25% in pickles or salad dressings?

A

Acetic acid

28
Q

What is acetic acid very effective against?

A

Bacteria

29
Q

How does acetic acid’s inhibitory mechanism work?

A

-neutralizing the electrochemical gradient of the cell membrane as well as denaturing proteins inside the cell walls.

30
Q

What has been recommended as carcass wash to reduce bacterial loads?

A

Acetic Acid

31
Q

What is propionic acid used in?

A

Used as salts of calcium or sodium in bread, cheese, jam, jellies, and tomato puree.

32
Q

What are the two microorganisms propionic acid is effective against?

A

Molds and Bacteria

33
Q

What is the antimicrobial action of propionic acid?

A

Acidification of the cytoplasm as well as destabilization of the membrane proton gradients.

34
Q

Where is lactic acid used?

A

As acid or as sodium or potassium salts up to 2%.

35
Q

Where can lactic acid be found?

A

Carbonated drinks, salad dressing, picked vegetables.

36
Q

What is lactic acid effective against?

A

Bacteria

37
Q

What is citric acid used in?

A

Used as an acid in >1% drinks, jams, jellies, baking products, cheeses, canned vegetables, and sauces.

38
Q

T/F: The antibacterial activity of citric acid is unclear.

A

true

39
Q

What is sorbic acid used as?

A
  • acid
  • salt of sodium, potassium, calcium
  • alcoholic and non-alcoholic drinks
  • processed fruits and vegetables
  • dairy desserts
  • confectioneries
  • mayonnaise
  • salad dressings
  • spreads
  • mustards
40
Q

What is sorbic acid most effective against?

A

Yeast and molds

41
Q

What is the antibacterial function of sorbic acid?

A

Inhibits the function of enzymes, the synthesis of the cell wall, protein, RNA, and DNA

42
Q

What is Benzoic acid used in?

A

-acid or sodium salt such as alcoholic and non-alcoholic drinks, processed fruits and vegetables, dairy desserts, confectioneries, mayonnaise, salad dressings, spreads, mustard.

43
Q

How does benzoic acid act?

A

Inhibits the action of enzymes needed for oxidative phosphorylation

44
Q

What is the order of the effectivity of natural acids?

A

From most effective to least effective:

  • acetic acid
  • propionic acid
  • sorbic acid
  • benzoic acid
  • lactic acid
  • citric acid
45
Q

What does an Aw of 0 indicate?

A

completely dry

46
Q

Where can osmophiles grow?

A

Environments high in sugar

47
Q

What type of environment can xerophiles grow in?

A

Very dry

48
Q

What are the three methods for removing water from food?

A

1- Dehydration
2-Crystallization
3-Adding solutes (salt, sugar, honey, starch)

49
Q

When is the hurdle concept most effective?

A

When it combines two stressors that act by different mechanisms

50
Q

What technique de-optimizes a variety of factors so that lower concentrations of each needed to inhibit bacterial growth?

A

Hurdle Concept

51
Q

What two bacteria can jump over the hurdle of a Pw of 0.97?

A

Listeria and Salmonella

52
Q

What bacteria can jump over the hurdle of pH of 5 and Aw of 0.97?

A

Listeria

salmonella cannot

53
Q

Why is an isobologram useful?

A

Can support the quantitative analysis of synergistic effects

54
Q

What are the effects if the point are on the line?

A

Additive effects

55
Q

What are the effects if the points fall below the line?

A

Synergistic effects

56
Q

What are the effects if the points are above the line?

A

Antagonistic effects

Foodborne Pathogens (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions