Spontaneous fermentation

I do not really believe cleanliness is the issue here. The vat would have to have been really noticeably unclean to have enough yeast to be at fault. I bet it was the fruit. Now to your question.

First most wild yeast is more sensitive to sulfite than domestic wine yeast so sulfite will slow it down or a day or so while the wine yeast becomes dominant. You probably hit a wild yeast that is less sensitive to sulfite than normal or it is possible your sulfite is old and has lost it's punch. It only has a shelf life of 6 months if exposed to air even in powdered form. It may have been old when you bought it if it was not sold in sealed glass containers. Read Jack Keller's site on shelf life of wine making chemicals. Also, you gave it a day and a half which is a bit long.

Second, sulfite is not an agent that will stop an ongoing fermentation. Once the fermentation is going you are not going to stop it with sulfite unless you add so much that it would ruin the wine.

Throw it out? No way! Either go with the wild yeast or introduce a domestic yeast anyway. The wild yeast may (or may not) have a low alcohol tolerance and may stick at between 5-10%. The domestic yeast could take over then and finish the wine. But go ahead and see what comes out of this. Do not give up prematurely.

Ray

I had that happen with a pineapple wine that I started last year. The campden tablets were put in same as every other batch, and when I went to pitch the yeast the next day it was bubbling away. Since pineapples are relatively inexpensive, I decided to let nature take its course on that batch and either bottle or toss it after a year. I'm still bulk aging it, about to bottle, but it seems okay (good, even).

It's up to you, but I'd probably try to go with what's there instead of risking an excess of sulphur in the finished wine. Too bad it was mulberry instead of something easily/cheaply purchased. :-(

Woods

There is a common misconception among home winemakers that sulfur dioxide "kills yeast." Therefore, wine yeast should not be added for 24 hours after adding sulfur dioxide. The 24 hour period is needed to allow the added sulfur dioxide to blow off.

This is _not_ the best way to use SO2 in wine.

Added SO2 stunts most of the native yeasts found on grapes and makes the native yeasts inactive for several hours. (Normal levels of SO2 will _not_ kill "wild" yeast).

Commercial "wine" yeast is _not_ effected by normal levels of SO2. So, yeast manufacturers recommend adding commercial wine yeast right after the sulfur dioxide is mixed into the must. The commercial yeast is unaffected, and it reproduces several generations of new yeast cells while the native yeast is till stunned. The commercial yeast cells then outnumber the native yeast cells many time over, so the added yeast dominates the fermentation..

Lum Del Mar, California, USA

Thanks for the info, I didn't know that.

Fortunately, it isn't a big problem, since the pineapples were pretty cheap and it didn't cost much to start the must. (Actually, in looking back through my records it was a pineapple mead that started on its own

- the honey was free, so it really only cost about $5 for a 5 gallon batch). If it works, fine, if not, not a huge loss if I toss it.

I'll definitely keep the SO2 advice in mind for future projects. ^_^

Woods

Anyway, you were all right. It fermented down to about 1.060 by itself (started at 1.10), it sat for a day and then picked up (I am assuming after the commercial yeast I added kicked in).

It did not taste funny or in anyway off either.

I just wonder why the morat that I made with the same berries (and the pomace from the wine, rinsed to extract color and leftover sugar) did not ferment spontaneously. I did not pasturized the honey at all, so you would think it would be more likely to take off by itself.