This is a quick post to clarify some confusion I have run into from a lot of home fermenters. The rise of the popularity of kombucha has brought the notion of the SCOBY (Symbiotic Culture Of Bacteria and Yeast ) to name the thick gelatinous mass that sits on top of kombucha fermentations.
Before this the more widely known and used term was mother of vinegar in vinegar fermentations. What is the difference, if any?
As the term SCOBY states, the mother (a biofilm made of cellulose) hosts not only acetic acid bacteria which make the cellulose for the SCOBY but also hosts yeast and other bacteria such as lactic acid bacteria. The reactions cam be complex but the yeast turn sugar into alcohol used by the acetic acid bacteria and the lactic acid bacteria can also ferment some compounds as well. The acetic and lactic acid bacteria also likely exchange DNA in a process called conjugation.
So a SCOBY is typically a SCOBY for all starting vinegar and kombucha fermentations when slow processes like vat or barrel fermentation are used. Both terms can work at this point. However, for vinegar around 1% acidity the yeast die off and at higher acidities the lactic acid bacteria die off as well leaving only acetic acid bacteria to feed on alcohol. At this point it is only a mother of vinegar containing one type of organism. Kombucha acidity usually ends between 0.5-1% while vinegar is 4% minimum and usually 5%. So calling a fermenting vinegar mother a SCOBY isn’t strictly accurate.