Food technology

1. Control of Microorganisms
Dr.Sunita Adhikari (Nee Pramanik)
Associate Professor, FTBE, JU

2. • Sterilization: Complete destruction of all living microorganism
either in vegetative or spore state.
• Disinfection: Destruction / removal of pathogenic organisms.
Sanitization is synonym of disinfection.
• Antiseptics: Chemical disinfectants which can be safely applied to
skin or mucous membrane and are used to prevent infection by
inhibiting the growth of bacteria.
• Bactericidal agents: Those are able to kill bacteria.
• Bacteriostatic agents: They prevent multiplication of bacteria but
they may remain alive.
A chemical may be bactericidal at a particular concentration and may
be bacteriostatic at a lower concentration.

3. How antimicrobial agents inhibit or kill?
• Damage to the cell wall or inhibition of cell wall
synthesis.
• Alteration of cell membrane permeability.
• Alteration of physical/ chemical state of protein and
nucleic acid.
• Inhibition of enzyme action.
• Inhibition of protein/ nucleic acid synthesis.

4. Physical agents
• High temperature
• Low temperature
• Desiccation
• Osmotic pressure
• Radiation
• Surface tension and interfacial tension
• Filtration

5. High temperature
Mode of action: Temperature above the maximum generally kill,
below the minimum produces statis. Temperature may be applied
in two forms.
a) Dry heat- Destroys the microorganism by oxidizing their
chemical constituents. e.g. Spores of Clostridium botulinum are
killed at 120 C in 2 hr.
b) Moist heat- It kills microorganism by coagulating their protein.
e.g. Spores of Clostridium botulinum are killed at 120 C in 4-20
min.