Pasteurization
In the 1860s, Louis Pasteur showed that gentle heating could stop wine from spoiling. Applied to milk, the idea went on to prevent more human disease than almost any other food intervention in history. Pasteurization is arguably the single most important food safety process ever invented.
Definition
Pasteurization is a heat treatment that destroys vegetative pathogens and most spoilage organisms in food — chiefly liquids like milk and juice — without the full sterilization that would ruin flavor and nutrition. The product still needs refrigeration (unless UHT-sterilized).
Key facts
- The methods: HTST (71.7°C/15 s, continuous — the dairy workhorse), batch/vat (63°C/30 min, for small-scale), and UHT (≥135°C for seconds — sterilizes for ambient storage).
- Each time-temperature combination targets the most heat-resistant pathogen of concern for that product — Coxiella burnetii for milk, for example. The numbers aren’t arbitrary; they’re validated against thermal-death data.
- Pasteurization kills vegetative cells, not spores — which is why pasteurized milk still spoils eventually and still needs the cold chain.
- The public-health record is extraordinary: pasteurization essentially eliminated milk-borne tuberculosis, brucellosis, and diphtheria transmission in countries that adopted it.
- Legal pasteurization includes the engineering: validated time-temperature, automatic flow diversion of under-processed product, continuous recording.
Why it matters
Raw milk outbreaks still happen regularly — Campylobacter, E. coli O157, Listeria — and they’re the clearest demonstration of what pasteurization prevents. The debate plays out emotionally, but the epidemiology isn’t emotional: pasteurized milk is one of the safest foods in the supply, raw milk one of the riskiest. For producers, the lesson is the engineering discipline around the heat treatment — validate, divert, record — not just the temperature itself.
Sources: FDA; ICMSF Microorganisms in Foods.
Quick reference
| Method | Time-temperature | Use |
| HTST | 71.7°C / 15 s | Milk, continuous |
| Batch (vat) | 63°C / 30 min | Small-scale |
| UHT | ≥135°C / seconds | Ambient-stable |
| Key point | Kills vegetative pathogens, not spores | Refrigeration still needed (except UHT) |