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Food Microbiology > Exam 1 > Flashcards

Exam 1 Flashcards

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1
Q

which kills more bacteria: slow or quick freezing?

A

slow

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2
Q

HACCP

A

control over raw materials, process, environment, distribution, and strorage as integrated preventative system

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3
Q

how do bacteria reproduce?

A

binary fission

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4
Q

generation time

A

time between divisions

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5
Q

lag stage

A

bacteria become accustomed to new environment - store nutrients, synthesize enzymes

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6
Q

log stage

A

active growth and fission; often symptoms

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7
Q

stationary stage

A

nutrients scarce, waste products accumulating, immuno-response from body

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8
Q

decline stage

A

further depletion of nutrients leading to cell death

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9
Q

factors affecting growth

A

food, acidity, time, temp, oxygen, moisture

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10
Q

most bacteria do not grow in pH

A

less than 4.6

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11
Q

danger temp zone

A

40-140 degrees F

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12
Q

microbes grow best at water activity

A

greater than 0.86

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13
Q

which can grow at lower water activity: bac or yeasts?

A

yeasts

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14
Q

hurdle concept

A

sub-lethal levels of growth-affecting factors are used in combo to reduce microbes

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15
Q

Q10

A

temperature coefficient for how fast microbes can metabolize

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16
Q

psychotrophs

A

microorganisms whose optimum growing range is 10-15 degrees C

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17
Q

blanching

A

immersion in hot water or steam to inactivate enzymes, reduce microbes, & fix color

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18
Q

fast freezing characteristics

A

small, intracellular ice crystals

thermal shock

19
Q

slow freezing characteristics

A

large, extracellular ice crystals
no shock
better at killing bacteria

20
Q

cold shock

A

dying of mesophiles upon sudden chilling

21
Q

sublimation

A

moisture evaporates into gas phase without going through the liquid phase

22
Q

radiation

A

emission of energy through space

23
Q

shorter wavelengths are more or less damaging to microorganisms?

A

more damaging to microorganisms

24
Q

ionizing radiation

A

carries enough energy to ionize molecules

25
Q

compton electron

A

electron that is ejected from outer shell of a molecule by ionizing radiation

26
Q

UV rays

A

have poor penetration, are non-ionizing, cause death due to mutations

27
Q

gamma rays

A

radiation emitted from nucleus of 60Co and 137Cs

28
Q

electron beam

A

stream of electrons emitted from radioactive substances that have poor penetration & use electricity as source

29
Q

x-rays

A

bombardment of heavy metal targets with high velocity targets

30
Q

radappertization

A

commercial sterilization (30-40 kGy)

31
Q

radicidation

A

pasteurization, reduction of pathogens (2.5-10 kGy)

32
Q

radurization

A

pasteurization, reduction of spoilage microbes (0.75-2.5 kGy)

33
Q

D value

A

time required to destroy 90% of initial microbial population at specific temp

34
Q

direct mechanism

A

targets DNA and RNA, breaks the base pairs, resulting in death of microorganisms

35
Q

indirect mechanism

A

result of free radicals’ generation that compromise cellular membrane

36
Q

free radicals

A

molecules with unpaired electrons

37
Q

1st chemical permitted in foods by the FDA

A

sodium benzoate

38
Q

effective against molds, yeasts & bacteria

A

sorbates

39
Q

specific against molds & fungistatic

A

propionates

40
Q

antioxidant in some foods

A

sulfites

41
Q

used in meat curing for color stabilization, flavor development & antimicrobial activity

A

nitrites & nitrates

42
Q

the perigo factor

A

heating food with nitrite yields agent 10x more inhibitory than nitrate alone

43
Q

preservatives that uses concentration of water to inhibit growth

A

salt & sugars

Food Microbiology (2 decks)

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