Theory:
Milk is a suspension. By introducing specific bacteria (Lactobacillus) and maintaining a consistent temperature, we convert lactose into lactic acid. This acidity coagulates the proteins, creating structure without mechanical force.
The Substrates (Ingredients):
- 1 Litre Whole Milk.
- 2 Tablespoons Active Yoghurt.
The Variables:
- Target Temp: 43°C – 46°C (110°F – 115°F).
- Incubation Time: 6 to 12 hours.
The Procedure:
- Denature: Heat the milk to 85°C (just before boiling) to restructure the proteins.
- Cool: Let the temperature drop to 46°C. This is crucial. Too hot, and you kill the bacteria. Too cold, and they sleep.
- Inoculate: Whisk the starter (yoghurt) into the warm milk. Do not over-agitate.
- Incubate: Pour into a glass jar. Wrap it in a thick towel and place it in a warm oven (turned off) or a cooler box.
- Wait: Close the door. Do not check it. Do not jiggle the jar. Let it sit in the dark for 8 hours.
- Set: Move gently to the fridge to halt fermentation.
Notes & Calibration
Density Modulation (Thicker Texture): To achieve higher viscosity (Greek-style), suspend the finished product in a muslin cloth or fine mesh sieve over a bowl. Allow gravity to filter out the whey for 6–12 hours in the refrigerator.
Analog Calibration (No Thermometer): If digital measurement is unavailable, rely on sensory thresholds:
- Cool limit: The substrate is ready for inoculation when a submerged finger can withstand the temperature for a full 10-second count without recoil.
- Heat limit: Cease thermal input when steam is visible and micro-bubbles begin to nucleate at the perimeter of the pot.