Fermentation speed...

Hi,

I pitched my yeast into an apple wine about 42 hours ago and the SG was 1.08. It's now at 1.07. Is that slow, fast, or normal in terms of yeast activity? Just want to make sure all is on track.

Normal... but why are you checking the SG so soon? If you don't want to risk infecting the batch, go ahead and leave that puppy for 3+ weeks before you go dipping stuff into it .

Sounds very normal to me. Don't mess a lot with it. The yeast know what to do.

Thanks, yeah, I hear you on not messing with it. I've got a strainer bag floating in there at the top full of apple pulp and thought I should give it a stir now and then. I also wanted to give the yeast a nice infusion of oxygen when I figured they were at their peak and just figured I'd test it while I was in there.

Is there a risk of anything nasty growing on the part of the fruit strainer bag that floats above the surface line of the liquid if I don't give it a stir here and there or does the carbon dioxide take care of that?

What ever I did, the thing is bubbling out of control ever since so I'm guessing the oxygen helped.

I think it would depend on your yeast as well, for apple I've been using Lalvin EC 1118. My primary doesn't show much activity until about the third day, then it really explodes. I use an "Ale Pale" with the airlock in the lid. For the yeast's oxygen need to multiply, I fit and empty airlock and a few times a day I push gently down on the center of the lid. You can hear the air rushing out from it, then release the lid after a second, pulling fresh air in. When I feel the need to do something like stirring it up, I tilt the pale slightly and gently swirl it. Change directions a few times. Around the third day, foam or liquid may burst into the airlock. This is when I re-sanitize the airlock and fill it to the proper level.