Microbial Control

Question 1

PHYSICAL MEANS OF MICROBIAL CONTROL

Answer 1

Moist heat vs Dry heat Microbial control by heat is
o Reliable
o Fast oRelatively safe o Inexpensive
oDoes not produce toxic substances into the material treated

Radiation

Filter Sterilization

Question 2

CHEMICAL MEANS OF MICROBIAL CONTROL

Answer 2

Chemicals that kill or inhibit the growth of microorganisms. They may be either synthetic chemicals or natural products.
– Bactericidal agent or bactericide: kills bacteria
– Fungicidal agent or fungicide: kills fungi
– Algicidal agent or algicide: kills algae
– Bacteriostatic agent: inhibits bacterial growth
– Fungistatic agent: inhibits fungal growth
– Algistatic agent: inhibits algal growth

Disinfectants and Antiseptics

Chemotherapeutic agents

Question 3

Disinfectants and Antiseptics

Answer 3

Disinfectants:
chemicals that kill microorganisms and are used on inanimate objects

e.g. chlorine gas, phenolic compounds, ozone.
 Antiseptics:
chemical agents that kill or inhibit the growth of microorganisms and are sufficiently nontoxic to be applied to living tissues
e.g. 70% alcohol, iodine solution, 3% H2O2 solution

Question 4

Methods of CONTROL OF MICROORGANISMS

Answer 4

STERILIZATION
• complete killing, destruction or removal of all microbial cells present
• Brought about by the use of heat, radiation, chemicals or filtration
• Once a product is sterilized, it will remain sterile indefinitely if it is
properly sealed

DISINFECTION
• process of eliminating most or all pathogens
• some viable microbes may persist.
• The term is used to describe the application of anti-microbial chemicals.
Chemicals used to disinfect inanimate objects are disinfectants (biocides = “kill life”)
they are also called germicides
If formulated to be used on the skin, it is called an antiseptic

PASTEURIZATION
• brief heat treatment (e.g. 60°C for 15 mins) to reduce the number of spoilage organisms and kill pathogens
• Suitable for foods such as milk and fruit juices that contain heat-sensitive substances

DECONTAMINATION
• treatment used to reduce the number of pathogens to a level considered safe to be handled, e.g. through washing, use of heat or disinfectant
PRESERVATION
• process of delaying spoilage of foods, by adding growth-inhibiting ingredients or adjusting storage conditions to inhibit microbial growth