Brainscape's Knowledge GenomeTM

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


See full index

FDSC 442 > 13 - Microbial Spoilage and Public Health Concerns pt 2 > Flashcards

13 - Microbial Spoilage and Public Health Concerns pt 2 Flashcards

1
Q

several milk spoilage bacteria can rely on what processes for energy generation?

A

proteolysis and lipolysis

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

lipolysis is favorable under what conditions?

A

at 4C. bc psychrotrophic bacteria have a faster growth rate here and produce lipases.

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

proteolysis is favorable under what conditions?

A

7C

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

what is the more common carbon source for bacterial spoilage in milk?

A

lactose

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

what are the main source of nitrogen in milk?

A

casein

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

what are non-protein nitrogen sources in milk?

A
  • urea
  • peptides
  • amino acids
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what are the major inhibitors of microbial growth in milk?

A

lactoferrin and lactoperoxidase

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

what does lactoferrin do?

A

binds iron, making it a limiting factor.

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

why isn’t lactoferrin as effective in cow’s milk as it is in human’s?

A

cow’s milk has more citrate which binds lactoferrin

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

what does lactoperoxidase do?

A

catalyzes the oxidation of thiocyanate and produces hypothiocyanite, a highly reactive oxidant

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

what are some of the less major natural inhibitors in milk?

A

lysozyme, specific immunoglobulins, folate, and vit B12

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

what is the limiting substrate in the lactoperoxidase system?

A

H2O2

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

adding H2O2 to milk will (increase/decrease) effectiveness of the lactoperoxidase system

A

increase

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

what microorgs are inhibited by the lactoperoxidase system?

A

LAB, coliforms, several pathogenic bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

true or false: it’s important to refrigerate raw milk before it’s pasteurized

A

true

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is the predominant bacteria in raw milk?

A

Pseudomonas sp.

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

what kind of respiratory bacteria will dominate spoiled refrigerated milk?

A

obligate aerobes

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

describe what happens to bacteria numbers over time during milk spoilage

A
  • enterobacteriaceae increase but are eventually overtaken by Pseudomonadaceae
  • if there’s spores, it’s usually from Bacillus genus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what does psychrotrophic milk spoilage rely on?

A

proteolysis. lipolysis to a lesser extent

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

what is the bacteria most associated with milk spoilage?

A

Pseudomonas sp.

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

can Pseudomonas sp. ferment lactose?

A

no

22
Q

what causes bitter and putrid flavors in milk?

A

proteolysis

23
Q

what causes rancid and fruit flavors in milk?

A

lipolysis

24
Q

what do wild LAB do to spoil milk?

A

produce unwanted gas or off-flavors due to production of other organic acids (acetic and propionic)

25
Q

what factors make dairy products spoil differently from milk?

A
  • nutrient composition
  • pH
  • water activity
26
Q

products with a (high/low) respiration rate can be stored for a long time

A

low

27
Q

what does ethylene do?

A

increases maturity

28
Q

what causes moisture loss?

A

respiration

29
Q

what is an appressorium?

A

structure at the end of a fungus’ germ tubes used to attach and penetrate plant surfaces by mechanical pressure

30
Q

how can pathogens enter plant material?

A
  • wounds

- natural openings

31
Q

fruits and vegetable have a (high/intermediate/low) water content

A

high

32
Q

what is the main limitation preventing growth of bacteria in fruits & veg?

A

pH

33
Q

what causes spoilage in low pH fruits & veg?

A

molds and yeasts

34
Q

what are some antimicrobial compounds found in plants?

A
  • tannins
  • phenolic compounds
  • sulfur-derived antimicrobials
  • terpenoids
  • phytoanticipins
  • phytoalexins
35
Q

storage close to what temperature is recommended for most fruits and veggies?

A

0C

36
Q

a RH of ____ is recommended for most fruits and veggies

A

90%

37
Q

what is the edible portion of a nut called?

A

seed, kernel, meat

38
Q

how are nuts preserved?

A

lowering aw below 0.7

39
Q

most nut spoilage is caused by _____

A

oxidation of nut fats

40
Q

what is the major spoilage organism associated w/peanuts?

A

Aspergillus flavus (the aflatoxin guy)

41
Q

when does microbial contamination of cereal grains happen?

A

when grains are growing

42
Q

what are the most common contaminants of cereals?

A

molds

43
Q

what are field fungi?

A

infect grain before harvest

44
Q

what are storage fungi?

A

infect grain after harvest

45
Q

list some field fungi

A
  • Alternaria
  • Cladosporium
  • Fusarium
  • Helminthosporium
46
Q

list some storage fungi

A
  • Aspergillus
  • Rhizopus
  • Mucor
  • Wallemia
  • Pennicillium
47
Q

does baking kill mold spores?

A

yes

48
Q

what is the main culprit of spoilage of baked products?

A

mold

49
Q

what kind of agents are added to bakery products to retard mold growth?

A

fungistatic

50
Q

bakery products with a moist interior are prone to _____ spoilage due to the bacteria called _____ _____

A

rope; Bacillus subtilis

FDSC 442 (14 decks)

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