Exam 1

Question 1

which kills more bacteria: slow or quick freezing?

Answer 1

slow

Question 2

HACCP

Answer 2

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

Question 3

how do bacteria reproduce?

Answer 3

binary fission

Question 4

generation time

Answer 4

time between divisions

Question 5

lag stage

Answer 5

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

Question 6

log stage

Answer 6

active growth and fission; often symptoms

Question 7

stationary stage

Answer 7

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

Question 8

decline stage

Answer 8

further depletion of nutrients leading to cell death

Question 9

factors affecting growth

Answer 9

food, acidity, time, temp, oxygen, moisture

Question 10

most bacteria do not grow in pH

Answer 10

less than 4.6

Question 11

danger temp zone

Answer 11

40-140 degrees F

Question 12

microbes grow best at water activity

Answer 12

greater than 0.86

Question 13

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

Answer 13

yeasts

Question 14

hurdle concept

Answer 14

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

Question 15

Q10

Answer 15

temperature coefficient for how fast microbes can metabolize

Question 16

psychotrophs

Answer 16

microorganisms whose optimum growing range is 10-15 degrees C

Question 17

blanching

Answer 17

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

Question 18

fast freezing characteristics

Answer 18

small, intracellular ice crystals

thermal shock

Question 19

slow freezing characteristics

Answer 19

large, extracellular ice crystals
no shock
better at killing bacteria

Question 20

cold shock

Answer 20

dying of mesophiles upon sudden chilling

Question 21

sublimation

Answer 21

moisture evaporates into gas phase without going through the liquid phase

Question 22

radiation

Answer 22

emission of energy through space

Question 23

shorter wavelengths are more or less damaging to microorganisms?

Answer 23

more damaging to microorganisms

Question 24

ionizing radiation

Answer 24

carries enough energy to ionize molecules

Question 25

compton electron

Answer 25

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

Question 26

UV rays

Answer 26

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

Question 27

gamma rays

Answer 27

radiation emitted from nucleus of 60Co and 137Cs

Question 28

electron beam

Answer 28

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

Question 29

x-rays

Answer 29

bombardment of heavy metal targets with high velocity targets

Question 30

radappertization

Answer 30

commercial sterilization (30-40 kGy)

Question 31

radicidation

Answer 31

pasteurization, reduction of pathogens (2.5-10 kGy)

Question 32

radurization

Answer 32

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

Question 33

D value

Answer 33

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

Question 34

direct mechanism

Answer 34

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

Question 35

indirect mechanism

Answer 35

result of free radicals' generation that compromise cellular membrane

Question 36

free radicals

Answer 36

molecules with unpaired electrons

Question 37

1st chemical permitted in foods by the FDA

Answer 37

sodium benzoate

Question 38

effective against molds, yeasts & bacteria

Answer 38

sorbates

Question 39

specific against molds & fungistatic

Answer 39

propionates

Question 40

antioxidant in some foods

Answer 40

sulfites

Question 41

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

Answer 41

nitrites & nitrates

Question 42

the perigo factor

Answer 42

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

Question 43

preservatives that uses concentration of water to inhibit growth

Answer 43

salt & sugars