What You Need to Know
During fermentation, thermophilic lactic acid bacteria such as Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus metabolize lactose to lactic acid, lowering pH and inducing casein micelle aggregation. In kefir, a symbiotic consortium also produces CO₂, trace ethanol, and exopolysaccharides that increase viscosity. Precise temperature and time control dictate acidity, texture, and safety, while pasteurization and cold storage prevent spoilage.
The Science
Primary Reaction
Fermentation of lactose to lactic acid, CO₂, and minor metabolites by thermophilic lactic acid bacteria or mixed bacteria‑yeast consortia