Final

Question 1

Sterilization

Answer 1

Removal or destruction of all forms of microbial life

Question 2

Commercial sterilization

Answer 2

limited heat treatment sufficient to destroy spores of Clostridium botulinum

Question 3

Disinfection

Answer 3

Control directed at destroying harmful microorganisms

Question 4

Antisepsis

Answer 4

disinfection applied to living tissue

Question 5

Determine

Answer 5

Mechanical removal

Question 6

Sanitization

Answer 6

lowering microbial counts to safe public health levels

Question 7

Bacteriostasis

Answer 7

does not kill but stops or stays further growth

Question 8

Asepsis

Answer 8

absence of significant contamination

Question 9

Biocide or germicide

Answer 9

‘cide’ to kill

Question 10

Microbial death

Answer 10

Death usually occurs at a constant rate

Question 11

Microbial control agents

Answer 11

Alteration of membrane permeability – get ‘leaky’ cells, loss of cellular contents

Damage to proteins and nucleic acids – loss of replication and metabolic function

Question 12

Microbial Control-Physical Methods

Answer 12

• Heat
• Filtration
• Low temperature
• High pressure
• Dessication
• Osmotic pressure
• Radiation

Question 13

What factors need to be taken into consideration for any control method

Answer 13

• Population size
• Population composition
• Concentration of agent
• Duration of exposure
• Local environment

Question 14

Microbial Control - Heat

Answer 14

Heat kills primarily through enzyme denaturation

Thermal Death Point (TDP)
Thermal Death Time (TDT)
Decimal Reduction Time (DRT)

Question 15

Thermal Death Point (TDP)

Answer 15

lowest temperature at which all microorganisms in a particular liquid will be 10 minutes

Question 16

Thermal Death Time (TDT)

Answer 16

minimum length of time for all bacteria in a particular liquid culture to be killed at a given temperature

Question 17

Decimal Reduction Time (DRT)

Answer 17

D value, time (min) in which 90% of a population of bacteria at a given temperature will be killed

Question 18

Moist heat

Answer 18

Kills microorganisms through the coagulation

Reliable sterilization requires higher temperatures achieved using steam under pressure

Steam at 15 psi (121oC) will kill all organisms and endospores in 15min

For proper sterilization– steam must penetrate all areas of the product

Question 19

Autoclave

Answer 19

free-flowing steam at 1atm 15 psi) at 121oC

• Putting steam under pressure brings its temperature higher
• Not everything will come out of the autoclave sterile
• There are rules for what you put in an autoclave so that it can be effective

Question 20

Pasteurization

Answer 20

Lowers microbial numbers and eliminates microorganisms

HTST = high-temperature short-time pasteurization
e.g. milk: 72oC for 15 seconds

Question 21

Dry heat sterilization

Answer 21

Flaming: material is heated to a red glow

Hot-air sterilization: items heated in a dry oven (170oC for 2h)

Question 22

Microbial Control - Filtration