Brainscape's Knowledge GenomeTM

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


See full index

FDSC 442 > microbial spoilage and public health concerns part 2 > Flashcards

microbial spoilage and public health concerns part 2 Flashcards

1
Q

milk is a great growth media for bacteria because of its ____, _____, and _____

A

high water content,
near-neutral pH,
available nutrients

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

why do we pasteurize milk?

A

to eliminate pathogens and increase shelf life

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

at what temperature does milk lipolysis happen faster?

A

4C

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

at what temperature does milk proteolysis happen fastest?

A

7C

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

____ are the main source of nitrogen for bacterial growth

A

casein proteins

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

what carbon is the most common carbon source in milk?

A

lactose, but glucose is also present in milk and serves to allow some growth of microbes

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

what non-protein nitrogen in milk is also readily available for microbial metabolism?

A

urea, peptides, and amino acids

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

what are the two 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
9
Q

why is lactoferrin an inhibitor of microbial growth?

A

lactoferrin binds iron which makes iron a limiting factor for bacterial growth in milk

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

why is lactoperoxidase an inhibitor of microbial growth?

A

survives pasteurization. catalyzes oxidation of thiocyanate when H202 and in the process creates hypothiocyanite which is a highly reactive oxidant and is antimicrobial

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

what other inhibitors are there of milk?

A

lysozyme, specific immunoglobins, and folate and vitamin B12 binding systems

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

hydrogen peroxide

adding a hydrogen peroxide generation system to the milk increases effectiveness of the lactoperoxidase system

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

what two things does the preservation of milk rely on?

A

effective sanitation (pasteurization) and refrigeration

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

what is the process of pasteurizing and refrigerating milk?

A

raw milk is kept cold until pasteurization after which it is kept cold again until consumption

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

what kind of bacteria are generally the ones responsible for spoiling both raw and pasteurized milk?

A

psychotrophic aerobic gram-negative rods

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

65-70% bacteria isolated from raw milk will be ______ spp.

A

Pseudomonas

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

what other psychrotrophic bacteria are present in milk?

A

Aeromonas, bacillus, listeria, staphylococcus, and Enterococcus

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

does psychrotrophic milk spoilage rely more on proteolysis or lipolysis to spoil the milk?

A

proteolysis

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

what bacteria are most associated with milk spoilage?

A

pseudomonas

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

____ are unable to ferment lactose

A

pseudomonas sp.

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

where does pasteurized milk become contaminated?

A

in milk processing plant equipment and air

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

what causes milk spoilage by LAB?

A

when the milk temperature is abuse, and is stored at temperatures sufficiently high for gram-positive acid-producers to outgrow psychrotrophic

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

what is the effect of “wild” LAB milk spoilage?

A

producing unwanted gas or off flavors due to the production of acetic acid and propionic acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

why do dairy products spoil differently than milk products?

A

other dairy products provide different environments, the pH has been altered, and the water activity differs

25
Q

why is hard to determine how spoilage occurs in fruits and vegetables?

A

a single produce item could be cultivated under several different conditions under many different climates.

26
Q

____ correlates negatively with the shelf-life of fruits and vegetables. what does this mean exactly?

A

respiration rate.
products with a high respiration rate have a short shelf life, products with a low respiration rate have a long shelf life.

27
Q

what compound increases produce maturity?

A

ethylene

28
Q

what does the aging process in fruits and vegetables lead to?

A

irreversible changes in the structure of fruit and vegetables, leading to deterioration

29
Q

Respiration also leads to ___ leading to ___ and wilting.

A

moisture loss

structural damage

30
Q

what is the significance of the cuticle barrier in spoilage of fruit and vegetable?

A

the cuticle barrier can be compromised by several spoilage bacteria by various enzymatic processes

31
Q

what is an appressorium?

A

a structure formed at the end of spoilage fungi’s germ tubes, which serves to attach and penetrate plant surfaces by mechanical pressure, initiating fungal spoilage

32
Q

What is the water content of fruits and vegetables?

A

> 95%, and contain a significant amount of nutrients essential for microbial growth

33
Q

spoilage of low pH fruits is caused by _____ and _____, which are more tolerant to high _____.

A

yeasts,
molds,
high acidity

34
Q

what antimicrobial compounds do fruits and vegetables contain?

A

tannins and phenolic compounds, sulfur-derived antimicrobials (onions or garlic), or terpenoids in carrots

35
Q

what are phytoalexins?

A

small molecules produced by plants in response to PAMPs on bacteria

36
Q

what are phytoanticipins

A

pre-existing phytoalexins that interact with a plant pathogen

37
Q

_____ may be involved in plant resistance

A

phytoanticipins

38
Q

what factors contribute to reducing respiratory activity in fruits and vegetables?

A

control of temperature, relative humidity, and composition of the gaseous atmosphere

39
Q

what storage temperature is recommended for fruits and vegetables?

A

0C

40
Q

what produce should not be stored at 0 Celcius due to chilling injuries

A

produce from tropical regions

41
Q

what relative humidity is recommended for most fruits and vegetables?

A

90%, except for garlic and onions

42
Q

what is the edible portion of the nut called?

A

seed, kernel, or meat

43
Q

how are nuts preserved?

A

lowering the water activity to below 0.7- prevents bacteria growth and increases shelf life

44
Q

what kind of nuts are peanuts?

A

ground nuts as opposed to a tree nut

45
Q

what is the significance of aspergillus flavus

A

a ubiquitous invader, and produces a mycotoxin is a major issue

46
Q

when does microbiological contamination occur in cereal grains?

A

while the grains are growing, and during and after harvest

47
Q

what limits the growth of microbes?

A

drying the grains and good storage practices

48
Q

what are the most common contaminants of grains?

A

molds

49
Q

what are field fungi?

A

molds that infect the grain before harvest

50
Q

what are storage fungi?

A

molds that infect grain after harvest

51
Q

what bacteria are considered field fungi?

A

Alternaria, Cladoporium, Fusarium, and Helminthosporium

52
Q

what bacteria are considered storage fungi?

A

Aspergillus, Rhizopus, Mucor, Wallemia, and Penicillium

53
Q

what can improperly dried grains lead to?

A

high mycotoxin levels

54
Q

what are some advantages to baking?

A

kills mold spores and vegetative microbial cells

55
Q

what is the predominant cause of baked product spoilage?

A

mold

56
Q

what happens to the surfaces of baked products while they are cooling and being packaged?

A

surfaces are re-contaminated with airborne mold spores

57
Q

most commercial bakery products contain one or more ____ agents to retard mold growth

A

fungistatic

58
Q

bakery products with a ____ interior are prone to rope-spoilage

A

moist interior

59
Q

what is rope spoilage due to

A

extracellular capsid material produced by bacillus subtilis

FDSC 442 (13 decks)

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