- ✓Raw milk carries a richer native microbiota and full native enzyme activity — usually more flavour complexity.
- ✓Pasteurisation removes pathogen risk and standardises the milk — usually more consistency.
- ✓Thermisation (gentle heating below pasteurisation) is a middle path used in many traditional cheeses.
What pasteurisation actually does
Pasteurisation is a heat treatment aimed at destroying pathogens. The standard options are HTST (High-Temperature Short-Time: 72°C for 15 seconds) and batch pasteurisation (63°C for 30 minutes). Both inactivate any pathogens present, and both also kill most of the native milk microbiota and denature some of the whey proteins. What survives: casein structure (mostly intact), milk fat (unaffected), and rennetability (close to unaffected, sometimes assisted by calcium chloride).
What raw milk brings that pasteurised doesn't
Raw milk contains a living microbial community — hundreds of species, many farm-specific, many pasture-specific. Some contribute directly to flavour; others act as adjuncts to added starters, pushing complexity in aged cheese. Raw milk also retains native milk enzymes, particularly lipases and proteases, that contribute to rich, characterful aging. Raw-milk cheese made well tends to have more flavour range and more variability batch to batch.
What pasteurised brings that raw doesn't
Consistency. Pasteurised cheesemaking is less variable — the milk starts from close to a blank canvas each time, and the added cultures dominate. Pasteurisation also sharply reduces pathogen risk from the milk supply, which is why it's mandated or strongly recommended for fresh and short-aged cheeses in most regions. Many excellent cheeses — including most supermarket cheese globally — are pasteurised.
Food-safety rules for raw-milk cheese vary widely by jurisdiction. Most commonly, raw-milk cheese must be aged at least 60 days before sale, based on research showing that time + acidity + salt typically renders pathogens undetectable. Local regulations matter — check yours before selling raw-milk cheese.
Thermisation: the middle path
Thermisation is a gentle heat treatment — typically 57–68°C for 10–20 seconds — that reduces pathogen and spoilage microbe counts without the full effect of pasteurisation. It keeps significantly more of the native microbiota and enzymes, while providing a safety margin. Many traditional cheeses — including some Gruyère, Comté, and raclette — use thermised milk as a compromise, retaining terroir character while meeting food-safety expectations.
Practical implications for home cheesemakers
- Hard aged cheese from raw milk: excellent if you can source clean milk from a trusted farm and age >60 days.
- Soft and fresh cheese from raw milk: higher risk — many cheesemakers use pasteurised milk for these.
- Supermarket milk (heavily pasteurised): works for most styles; often benefits from calcium chloride addition.
- UHT milk: do not use for cheese — the protein is too altered to coagulate properly.
Frequently asked
Is raw-milk cheese legal where I live?+
Depends. In the UK and most of Europe, raw-milk cheese is legal with aging and labeling rules. In the US, interstate sale of raw-milk cheese requires 60+ days of aging; some states ban retail sale of any raw-milk cheese. Check local regulations carefully.
Can I pasteurise my own milk?+
Yes, with a thermometer and a double boiler — hold at 63°C for 30 minutes, cool rapidly. Do it properly (with stirring, a clean vessel, and rapid cooling) and the result is closer to home pasteurisation than supermarket ultra-pasteurisation, which is better for cheesemaking.
