The dominant color of my scoby is, for lack of a better color vocabulary, light plum. But there are some whiteish bits which concern me a bit. I would say it smells fairly fresh (and sour) and tastes pretty good. Any thoughts?
If the white bits are on the top, it is probably a mold. I once got this when I tried using honey as a sweetener instead of sugar. To get rid of the mold I first skimmed all of the white bits off the tea and then poured most of the brewed tea out except for a very very small amount. I then rinsed my scoby and added it to the small amount of brewed liquid and a new batch of tea and it was fine. Mothers are very adaptable and hard to annoy so often the problems are in the tea rather than the organism, but it is important to not let cultures grow. If this sounds like your issue, I would suggest doing the same.
What you need to be concerned about is the color of the scoby itself. If the daughter created looks discolored, that could be a problem. If the mother still looks fine you can throw out the daughter and make a new batch and see what happens. Otherwise if you have a reserve mother you keep in a jar in your fridge or cabinet, it might be a good time to start using it instead.
Yes, +1 on white spots being mold. You can dump the batch and wash the SCOBY in white vinegar to try to save it (but it's better to just dump it). FWIW, mold is caused by 2 things, but basically it's not getting your pH low enough fast enough:
- Not enough sugar
- Not enough starter / too high a pH
If you want less sugar in your kombucha, let it brew longer, don't use more at the beginning. It fuels the growth of yeast and bacteria, and is consumed in the process. If you put in too little, the yeast and bacteria can't take hold, the pH doesn't drop enough, and mold forms. Also, start with a lot of starter (a couple bottles of any live, raw kombucha will work if this is your first batch, or save some of the last batch) so that there's enough bacteria and yeast to seed it, and also so that the pH is low. You want the pH on the final product to be somewhere between 2.6 (really acidic) and 3 (the high point, above this you can get mold or possibly other bad organisms like botulism).