Kefir

In recent years, I have developed a taste for buttermilk. It started when I began keeping a sour dough starter and found a recipe for buttermilk waffles. Soon I began drinking it straight. Last year in Turkey, I found a drink there called kefir which tasted similar to the buttermilk I knew. I was surprised to find It in a grocery in Slovakia without any sophisticated labeling. It must be produced locally. So I did some reading, I.e. looked it up in Wikipedia, and found that there is evidence of fermented milk products going back ten thousand years as a way of allowing the preservation of milk before refrigeration. In particular, kefir is popular throughout Eastern and Northern Europe, Russia and Central Asia. Like buttermilk, the lactose is converted to lactic acid, but it also utilizes yeast to encourage fermentation. How much depends on the time allowed. Left longer, and using horse milk, you get the  "mare's milk" liquor that my husband sampled in Kyrgyzstan.