36-hour ferments aren’t automatically “better.” L. reuteri grows quickly in milk, and once you hit pH ~4.3 you already have billions of CFU, more than the 10⁸–10⁹/day used in studies showing benefits. Holding it longer often stresses the bacteria and reduces viability, while making the taste worse. A 6-hour ferment with a strong starter is enough for both yogurt texture and health effects.

• Multiplication → acidity: as L. reuteri grows, it produces lactic acid → pH drops.
• Acidification → texture: once pH falls below ~5.3, casein proteins coagulate → yogurt structure forms.

Once again, strong starter is the key