Stuck second fermentation - suphites to blame?

Question

I'm making a sparkling elderflower wine. It's in a 25l plastic bucket with a trap. The first fermentation went well. I racked it, added sulphites (Campden tabs), added fining, left for a couple of months. At this point the wine smelled great, but had a bitter aftertaste (not acidic), probably a bacterial effect, so I racked again and filtered, giving me a nice clear wine that tasted fine, with an alcolohol content of about 6.4%.

After reading various articles on sparkling wine making, I added more Campden tabs (a smaller amount) to ensure there were no more bacteria and left it for 2 days for it to gas out. Then I added yeast and a sugar solution for the secondary fermentation and bottled it. Now I'm finding that the fermentation is stuck - after a week, there is nothing happening in the bottles, no gas production at all. I've read that sulphites should be gone within a day or two, so it's OK to use them for sparkling wines if they are given time. I've also read that though sulphites are often used to 'kill' yeasts, they don't apparently kill them, just slow them down.

Is my second fermentation dead? Or do I just need to give it more time?

Update

As the posted answers suggested it might, this did eventually kick off and it'a been a success overall. I'm still getting a slight bitter aftertaste, so this year I'll get the sulphites in earlier to make sure I kill off any bacteria before they get a chance to take hold.

Answer 1

The temperature could be a factor, make sure your bottles are stored at a correct temperature (see the yeast package for ideal temperature).

It is possible that the SO2 did not evaporate as much as expected? There are kits that you can buy to measure sulfites in wine : Titrets

It is also possible that the yeast in the bottles did not get enough oxygen to reproduce properly. Splash-racking before bottling could have helped you to get rid of some SO2 and add some oxygen at the same time.

Since bottling is done, I would shake the bottles gently (to stir the yeast) and wait 2-3 more weeks, it might still ferment.

Answer 2

Campden tablets are usually Potassium Metabisulfite .It works by depriving organisms of oxygen, kinda like how halon puts a fire out. For yeast it means it doesn't have what it needs so it's waiting, doesn't kill it.

I've made cider from juice that used Potassium Metabisulfide as a preservative, fermination would only start once the preservative was defeated by injecting pure o2 gas, about 3x what I normally would for oxygenating wort.

I wouldn't recommend o2 post fermination. You may have to make do with a still cider, or keg and force carb it.