Fermentation until now has always followed the same pattern.
First there is the lag phase as the yeast multiplies
Followed by a vigorous phase generally with some foam
After which the foam disappears and the fermentation slows over time until it eventually quits.
This year I had one carboy go through a vigorous stage but with little foam before slowing to what I thought was going to be a steady fermentation. But somehow it went through a second vigorous phase with foam that push all the way through the airlock.
Background on this. I have two carboys from the same harvest. Essentially the same chemistry with very slight differences due to the press juice in one. Cleanest fruit I have ever harvested. Considered letting it go spontaneously but the wife didn’t want to risk it. Hit it with some SO2 and let it settle. Racked off the muck and pitched. Once carboy took but the other didn’t. Figured it was old yeast so repitched and it still didn’t take. Things get fun now as I tried a number of things. Pulled juice from the carboy that started, pitched a different yeast as well as more of the original yeast that I found in the back of the refrigerator. Eventually, something started and I did notice that fermentation looked different than the carboy that started first. That carboy had foam during the vigorous phase where this second one did not in what turned out to be the first phase. There is no off orders. In fact it smells wonderfully of mango.
Any ideas what happened? I am guessing that the first fermentation was a delayed spontaneous that was eventually overcome by whatever viable yeast I pitched and this explains the two vigorous phases with different foam production.