What You Need to Know
The process relies on the metabolic activity of Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus, which convert lactose into lactic acid and CO₂. The controlled temperature optimizes enzyme kinetics while preventing casein denaturation, preserving the protein matrix and yielding a smooth, creamy texture. The pH drop to around 4.5 stabilizes the yogurt and inhibits spoilage organisms.
The Science
Primary Reaction
lactose → lactic acid + CO₂ (by Lactobacillus delbrueckii subsp. bulgaricus & Streptococcus thermophilus)