A fermented milk drink with a sour taste is commonly known as kefir or soured milk. Kefir is a fermented probiotic milk drink made by adding kefir grains (a mix of bacteria and yeast) to milk, which ferments the lactose into lactic acid and other compounds. This fermentation process gives kefir its characteristic sour, tangy flavor along with a slightly effervescent (carbonated) quality and a creamy texture. Kefir is thicker than sour milk and has a more complex and balanced flavor due to the controlled fermentation by specific microbes, including lactic acid bacteria and yeast. It can also have a slight alcohol note and is considered a healthful drink with probiotic benefits.
Soured milk refers to milk that has been acidified either by fermentation through lactic acid bacteria or by adding acids like lemon juice or vinegar. Fermented soured milk has a tart taste and thicker consistency compared to regular milk and contains less lactose. It is consumed in many regions worldwide and may be produced naturally or commercially.
In summary, kefir and soured milk are both fermented milk drinks that have a sour taste, but kefir is distinct in having a richer microbial diversity, a creamy texture, slight effervescence, and more nuanced flavors compared to simpler soured milk.
Thus, the answer: The fermented milk drink with a sour taste is kefir or soured milk, with kefir being a more complex, cultured fermented milk drink widely recognized for its probiotic benefits and distinct sour flavor.
