The vivid purple color doesn't come from the turnip itself but from purple carrots fermented alongside it — turnip only lends the name and a sharper bite.
A deep purple, sour-salty drink made by fermenting purple carrots, sometimes with turnip, together with bulgur flour, salt and a sourdough starter, şalgam is served ice-cold, either plain or spiked with chili. It's the standard companion to Adana kebab, drunk straight from the glass between bites.