Write two numbers, not one. Vat temperature is who you hired. Cellar temperature is how long they get to work. Mixing them up is how a log becomes fiction.

In the vat

Mesophilic cultures (often Lactococcus lactis) work in a band around 20–30°C. Thermophilic Streptococcus thermophilus and some lactobacilli sit nearer 35–45°C. So 32°C and 38°C pick different shifts. Acid speed changes. Bitterness risk later changes with it. West Country Farmhouse Cheddar’s specification scalds curd between 39.4°C and 41°C. Mozzarella di Bufala Campana’s public notes put the vat around 33–36°C, then stretch water near 95°C. Those are not interchangeable rooms.

In the cellar

Aging is another building. Many bloomy cheeses like roughly 8–14°C and high humidity. Hard wheels often sit near 10–15°C. Specifications get more precise: Camembert de Normandie writes 10–18°C. Taleggio’s consortium writes 1–6°C and humidity above 80%. Put the probe in the curd, not on the pot wall. In a cellar, air temperature and rind temperature are often not the same number.

Steps worth logging

• Milk in. Temperature of the milk, not the room.
• Set. Temperature at rennet, and minutes to a clean cut.
• Cook or not. Peak vat temperature, to the degree.
• Cave or fridge. Daily air reading, and whether the wheel was turned.

Common mistakes

Calling a kitchen “cool” instead of writing 12°C. Using a wall thermostat as if it were the paste. Holding a bloomy cheese at hard-cheese cellar heat and then blaming the culture. Leaving a soft cheese between 4°C and 60°C for a picnic and calling it affinage.