Exam 2

Question 1

thermodurics

Answer 1

survive in relatively high temps but do not necessarily grow

Question 2

thermophilics

Answer 2

not only survive high temps but require them for their growth

Question 3

sterilization

Answer 3

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

Question 4

commercially sterile

Answer 4

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

Question 5

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

Answer 5

increases

Question 6

are moist or dried microbial cells more heat resistant?

Answer 6

dried

Question 7

heat resistance (increases/decreases) with presence of fat

Answer 7

increases

Question 8

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

Answer 8

long chain fatty acids

Question 9

how does fat presumably affect resistance?

Answer 9

by directly affecting cell moisture

Question 10

salts (increase/decrease) resistance

Answer 10

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

Question 11

sugars/carbs (increase/decrease) resistance

Answer 11

increase

Question 12

how does pH affect resistance?

Answer 12

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

Question 13

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

Answer 13

higher

Question 14

cells are most resistant in which phase?

Answer 14

stationary phase

Question 15

cells are least resistant in which phase?

Answer 15

log phase

Question 16

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

Answer 16

greater

Question 17

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

Answer 17

more resistant

Question 18

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

Answer 18

Gram+

Question 19

which is more resistant, cocci or rods?

Answer 19

cocci

Question 20

some factors for why spores are so heat resistant

Answer 20

protoplast dehydration, mineralization, thermal adaption

Question 21

thermal death time

Answer 21

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

Question 22

d-value

Answer 22

time required to destroy 90% of organisms

Question 23

12-D concept

Answer 23

lethality requirement in effect in the canning industry

Question 24

z-value

Answer 24

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

Question 25

important thermophiles

Answer 25

bacilli, clostridia, LAB

Question 26

minimally processed foods

Answer 26

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

Question 27

how do microwave and radio-frequency heating work?

Answer 27

by using electromagnetic waves to generate heat in food

Question 28

2 mechanisms by which mv and rf heat

Answer 28

dielectric and ionic

Question 29

ohmic heating

Answer 29

alternating current passes through electricity-conducting foods

Question 30

pulsed electric field

Answer 30

pulses of high electric field to food between 2 electrodes

Question 31

electroporation

Answer 31

production of pores in membranes by the electric current

Question 32

manothermosonication

Answer 32

simultaneous heating and ultrasonic waves that reduce spore resistance

Question 33

high intensity pulsed light

Answer 33

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

Question 34

indicator organisms

Answer 34

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

Question 35

food-borne illness

Answer 35

any illness resulting from ingestion of food

Question 36

infection

Answer 36

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

Question 37

intoxication

Answer 37

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

Question 38

endotoxins

Answer 38

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

Question 39

exotoxins

Answer 39

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

Question 40

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

Answer 40

staphylococcal aureus

Question 41

how can one test for S. aureus?

Answer 41

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

Question 42

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

Answer 42

non-proteolytics

Question 43

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

Answer 43

proteolytics

Question 44

most lethal type of botulinal neurotoxin

Answer 44

type A

Question 45

pasteurization

Answer 45

destruction of all disease-producing organisms