Brainscape's Knowledge GenomeTM

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


See full index

Micro > Microbial Control In Foods > Flashcards

Microbial Control In Foods Flashcards

1
Q

Examples for biological control of microbial growth ?

A

Controlled acidification, bacteriocin, probiotics

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

Actions of microbial control agents

A

Alternation of membrane permeability
Damage to proteins
Damage to nucleic acids

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

Effectiveness of antimicrobial treatment depends on

A

Number of microbes
Environment
Time of exposure
Microbial characteristics

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

Heat treatments used commercially

A

Blanching

Pasteurization

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

What is blanching

A

Briefly pass through boiling water

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

Does pasteurization kill all the pathogens

A

No

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

Pasteurization —–pathogens
Kill ?
Inactivates ?

A

Inactivates

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

What is the major site of sub-lethal heat induced injury

A

Cell membranes

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

Destruction of a pure culture , by moist heat at a constant temperature, results in…

A

Negative exponential kinetics

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

Bacterial death is

A

Logarithmic

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

D value aka

A

Decimal reduction time

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

What is D value ?

A

Time necessary at T to reduce the population by 90%

Or time necessary at T for the survivor curve to transfer one log cycle

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

1 log reduction means

A

90% reduction,

10% survival

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

When D value is higher the survivor curve

A

Is flatter because it takes longer to have 1 log reduction

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

D values are —- specific

A

Process

Temperature

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

Z value

A

Temperature change to result in a 10 fold change in the D value

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

What is autoclave

A

Steam under pressure

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

Classic method of pasteurization

A

Milk was exposed to 65 C for 30 min

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

What is the pasteurization method used for milk today

A

High temperature short time pasteurization (HTST)

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

HTST

A

Milk is exposed to 72 C for 15 sec

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

Ultra high temperature pasteurization

A

Milk is treated at 140 C for 3 seconds and then cooled every quickly in a vacuum chamber

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

What is the advantage of milk pasteurization

A

Pasteurized milk can be stored at room temp for several months

23
Q

Freezing

A

Temp below 0

24
Q

Freezing can be divided to

A

Flash freezing

Slow freezing

25
Q

Does flash freezing kill most bacteria

A

No

26
Q

Why is slow freezing harmful

A

Ice crystals disrupt cell structure

27
Q

What is lyophilization

A

Freeze drying

28
Q

Advantage of sublimation

A

Texture will be less affected

29
Q

What is an essential oil ?

A

Concentrated hydrophobic liquid containing volatile aroma compounds from plants

30
Q

What kind of essential oils have antimicrobial effects on fresh produce

A

Clove
Basil
Lemongrass
Thyme

31
Q

What is the effect of emulsifier on emulsion

A

Stabilize it

32
Q

Why do we ferment foods

A
  • Food preservation
  • Change in organoleptic characteristics
  • Money
33
Q

Fermentation takes place in the presence or absence of oxygen

A

Absence

34
Q

What are the major fermentation used

A

Lactic
Propionic
Ethanolic

35
Q

Most important bacterial starter cultures

A

Lactate Acid Bacteria

LAB

36
Q

Bacterial started cultures belong to 4 categories

A

Lactococcus
Streptococcus
Lactobacillus
Leuconostoc

37
Q

How is yogurt produced

A

By the controlled fermentation of milk by 2 species of bacteria

38
Q

What are the 2 species of bacteria that are used in making yogurt?

A

Lactobacillus bulgaricus

Streptococcus thermophilus

39
Q

How does curd form in yogurt ?

A

The sugar in milk called lactose is fermented to lactic acid and it is this that Caucasus the characteristic curd to form

40
Q

How does streptococcus thermophilus affect milk

A

Brings the PH down to 5.5

41
Q

How does lactobacilluls Bulgaria help in making yogurt

A

It converts lactose to lactic acid

42
Q

At the end of incubation pH may fall to as low as

A

4.2-4.4

43
Q

——-coagulates the remaining milk proteins causing the yogurt to thicken

A

Lactic Acid

44
Q

What gives raw yogurt its characteristic flavor ?

A

Acetaldehyde

45
Q

What is bacteriostatic effect

A

Low temp Reduces metabolic rate of most microbes so they cannot reproduce or produce toxins

46
Q

What is fermentation ?

A

Any partial breakdown of carbohydrates taking place in the absence of oxygen

47
Q

How is acetalehye produce

A

It is a metabolic by product of both species

48
Q

How long is the incubation of yogurt

A

12 hrs at 32 C

49
Q

How does homogenization make pasteurized milk more stable ?

A

It makes fat globule smaller

50
Q

What is the liquid portion of milk called after treatment with rennin

A

Whey

51
Q

Where do they obtain rennin from

A

From the stomach of young calves

52
Q

What does rennin do

A

It causes the milk protein ( casein ) to clabber

53
Q

In Cheese making milk is treated with what bacteria

A

Lactic acid bacteria and enzyme called Rennin

54
Q

Before being sold and eaten, the cheese must age how long ?

A

From 60 days to several years

Micro (9 decks)

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