Description
Cultures that convert lactose into lactic acid and other metabolites to produce yogurt and kefir.
Technical
During yogurt fermentation, *Lactobacillus delbrueckii* subsp. *bulgaricus* and *Streptococcus thermophilus* enzymatically reduce lactose to lactic acid, lowering pH to ~4.5 and inducing casein micelle coagulation. In kefir, a symbiotic consortium of lactic acid bacteria, yeasts, and acetic acid bacteria produce lactic acid, ethanol, CO₂, and the polysaccharide kefiran, creating a complex, slightly effervescent matrix.
Science
Primary Reaction
lactose → lactic acid (yogurt) or lactic acid + ethanol + CO₂ + kefiran (kefir)
Sensory Profile
Aroma ()
milkysweetacidicyeastybutterytangyearthy
Origin & History
Civilization