I'm about one week into growing my first SCOBY that I can use to make my own kombucha. I opted to grow my own instead of purchase one just because it looked simple enough. I took a whiff of the brew today, and it smells strongly of vinegar. The process was pretty simple: make sweetened black tea, let it cool, added some store bought plain kombucha, put it all in a jar and covered it with a cloth. Is it normal for it to smell like vinegar?
Yes it should.
To quote Sandor Katz from The Art of Fermentation:
'Many people have observed that the kombucha SCOBY is identical, or virtually so, to the mother-of-vinegar that often forms on the surface of fermenting vinegar. Some have even described kombucha as immature vinegar.'
So it's perfectly fine it smells that way (in fact it's an indication everything is going well). The trick with kombucha is (typically) to refrigerate it and drink it while there's still some sugar left and before it becomes unbearably sour (meaning before it is fully fermented/matured).
answer edited. Different SCOBYs contain different biological agents and the makeup can vary. Even the "same" SCOBY varies from environment to environment. However I accept that the most common and traditionally grown kombuchas produce more acetic than lactic acid. So smelling of vinegar can be a normal odour for Kombucha.