
Yoghurt is a fermented dairy product made by culturing milk with lactic-acid-producing bacteria until it coagulates into a thick, tart semi-solid.
Soft lactic tartness over a creamy, mild dairy base, low in sweetness with little aroma.
Used in generous, spoonable measures rather than dashes, yoghurt supplies body, opacity and a gentle acidity to blended and shaken dairy-forward drinks; its viscosity means it must be blended, stirred or shaken vigorously rather than poured. Being acidic, it is prone to curdling when combined with strongly acidic or high-alcohol ingredients, or when heated.
As a bulk body ingredient it is essentially not swappable; where a small accent is needed, another thick cultured dairy such as buttermilk or strained labneh-style dairy preserves the creamy body and lactic tartness, with any missing sweetness added separately by sugar or syrup.
Kefir
Kefir is a fermented milk drink made with kefir grains, a symbiotic culture of multiple bacteria and yeasts, and is typically thin, drinkable and sometimes slightly effervescent or mildly alcoholic; yoghurt is set by a defined bacterial culture, is thicker, and is non-alcoholic.
Cultured from milk or milk products with lactic-acid bacteria — traditionally Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus — yoghurt sets as fermentation coagulates the milk. The bacteria produce lactic acid, lowering the pH to thicken the milk and give it a sour edge. It is a non-alcoholic dairy food and carries no meaningful alcohol content.
A perishable refrigerated product with live cultures; keep chilled and use before its date.