Which sterilization method is appropriate for heat-sensitive liquids?

• A. Filtration
• B. Dry heat
• C. Steam sterilization
• D. Gas sterilization

Answer: (A)

When a liquid cannot tolerate heat, removing microorganisms without heating is the practical approach. Filtration sterilization uses a sterile membrane to physically remove microbes from the liquid, preserving its chemical integrity and activity. A typical sterilizing filter (pore size around 0.22 micrometers) traps bacteria and fungi, providing a sterile product without exposure to steam or dry heat that could damage the liquid. Other methods rely on heat or chemical exposure: steam and dry heat require high temperatures that would degrade heat-sensitive liquids, while gas sterilization, though useful for some items, introduces residues and handling challenges for liquids and is not the standard choice for direct liquid sterilization. Filtration thus effectively sterilizes heat-sensitive liquids while maintaining their properties.