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Food Microbiology > Exam 2 > Flashcards

Exam 2 Flashcards

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1
Q

thermodurics

A

survive in relatively high temps but do not necessarily grow

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2
Q

thermophilics

A

not only survive high temps but require them for their growth

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3
Q

sterilization

A

destruction of all viable organisms as may be measured by enumerating technique

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4
Q

commercially sterile

A

no viable microbes can be detected by the usual methods or the number of survivors is so low it is insignificant

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5
Q

heat resistance of microbial cells (increases/decreases) with decreasing humidity, moisture, or Aw

A

increases

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6
Q

are moist or dried microbial cells more heat resistant?

A

dried

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7
Q

heat resistance (increases/decreases) with presence of fat

A

increases

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8
Q

which is better at fat protection: long chain or short chain fatty acids?

A

long chain fatty acids

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9
Q

how does fat presumably affect resistance?

A

by directly affecting cell moisture

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10
Q

salts (increase/decrease) resistance

A

it depends on the type/concentration of salt used; some provide protective effect by decreasing Aw, while some increase Aw and heat sensitivity

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11
Q

sugars/carbs (increase/decrease) resistance

A

increase

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12
Q

how does pH affect resistance?

A

most resistant at optimum pH (usually neutral). as pH deviates from optimum value, resistance decreases

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13
Q

the larger the number of organisms, the (higher/lower) the heat resistance

A

higher

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14
Q

cells are most resistant in which phase?

A

stationary phase

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15
Q

cells are least resistant in which phase?

A

log phase

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16
Q

heat resistance is (greater/lesser) when the incubation temp is higher

A

greater

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17
Q

are spore-formers more or less resistant than non-spore-formers?

A

more resistant

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18
Q

which is more heat resistant, Gram+ or Gram-?

A

Gram+

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19
Q

which is more resistant, cocci or rods?

A

cocci

20
Q

some factors for why spores are so heat resistant

A

protoplast dehydration, mineralization, thermal adaption

21
Q

thermal death time

A

time necessary to kill a given number of organisms at a specified temp

22
Q

d-value

A

time required to destroy 90% of organisms

23
Q

12-D concept

A

lethality requirement in effect in the canning industry

24
Q

z-value

A

temp increase that causes 1-log change of d-value

25
Q

important thermophiles

A

bacilli, clostridia, LAB

26
Q

minimally processed foods

A

quality of fresh foods without conventional food preservation, convenient to prepare, serve, and consume

27
Q

how do microwave and radio-frequency heating work?

A

by using electromagnetic waves to generate heat in food

28
Q

2 mechanisms by which mv and rf heat

A

dielectric and ionic

29
Q

ohmic heating

A

alternating current passes through electricity-conducting foods

30
Q

pulsed electric field

A

pulses of high electric field to food between 2 electrodes

31
Q

electroporation

A

production of pores in membranes by the electric current

32
Q

manothermosonication

A

simultaneous heating and ultrasonic waves that reduce spore resistance

33
Q

high intensity pulsed light

A

pulses of intense broad spectrum light are used as a surfaces treatment

34
Q

indicator organisms

A

used to relate microbiological quality in terms of product shelf-life and safety

35
Q

food-borne illness

A

any illness resulting from ingestion of food

36
Q

infection

A

infectious bacteria invade and colonize the intestinal tract, disrupting uptake of solutes, causing osmotic pressure imbalance

37
Q

intoxication

A

bacteria produce toxins in food, then toxins are rapidly absorbed in the GI tract

38
Q

endotoxins

A

composed of LPS in the cell wall of Gram- bacteria, released when the cell dies and induces a fever

39
Q

exotoxins

A

proteins, generally associated with Gram+ bacteria, usually synthesized in and secreted by living cells

40
Q

what did Denys and Barber study in the late 19th/early 20th century?

A

staphylococcal aureus

41
Q

how can one test for S. aureus?

A

catalase (H202) and coagulase tests (clot formation=positive)

42
Q

which type of strains of C. bot is favored by carbohydrates?

A

non-proteolytics

43
Q

which is more heat resistant: proteolytics or non-proteolytics?

A

proteolytics

44
Q

most lethal type of botulinal neurotoxin

A

type A

45
Q

pasteurization

A

destruction of all disease-producing organisms

Food Microbiology (2 decks)

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