Which method is a classic example of sterilization?

• A. Boiling water
• B. Pasteurization
• C. Autoclaving
• D. Chemical disinfectants

Answer: (C)

Sterilization means destroying all forms of microbial life, including hardy spores. Autoclaving is the classic method for achieving this because it combines moist heat with high pressure to reach temperatures well above boiling. The steam under pressure penetrates materials and, at the elevated temperature (around 121°C) for a typical period (about 15–20 minutes), rapidly denatures proteins, disrupts membranes, and damages nucleic acids, ensuring even resistant spores are killed. That combination of heat, moisture, and pressure provides a reliable, validated process used for critical items like surgical instruments, culture media, and lab glassware.

By contrast, boiling water can kill many vegetative bacteria but doesn’t reliably inactivate spores. Pasteurization reduces the microbial load and targets pathogens in foods but is not designed to achieve sterility. Chemical disinfectants can kill many organisms but often do not guarantee complete sterilization, especially against spores, unless used in specialized, sometimes hazardous, sterilant protocols.