Stopping fermentation

I have been planning to make a root-beer flavored beer. It'll probably have at least a partial malt extract base and I'm hoping for at least a few percent alchohol, but hopefully not too much. Root beer is quite sweet and it calls for a lot of unfermented sugar.

In regular soda making when they use yeast to carb the sodas, the technique seems to be to just toss the stuff in the fridge to send the yeast into hibernation so it stays sweet, doesn't explode, and doesn't turn into some kind of mead wine from the 4lbs of straight sugar.

I'm thinking I should be able to do this 3 days into primary fermentation with 3%-5% alchohol and still keep (or add to taste) unfermented sugars for sweetness.

But I've also noticed that for meads, ciders and wines etc, people use camden tablets and potassium sorbate to do this, especially when they want to add sugars to sweeten, although that seems to be only for when they're not looking for carbonation.

Is this because champagne yeasts withstand colder temperatures and higher pressures in the bottle than an ale yeast would? Can I take a beer that's been half fermented and stop it by tossing it in the fridge, to keep the sugars unconverted or 'back-sweeten' with more sugar without causing bottles to explode? Or is there a better way?

My thoughts on a non-fermentable sugar like lactose is that it wouldn't taste the same.

I was thinking of using Wyeast Beglian Saison to try this, both because it has a very high temperature range (70-95 deg. F) which should make it easier to put to sleep in the fridge, and also because Wyeast's website description says this:

"This strain is notorious for a rapid and vigorous start to fermentation, only to stick around 1.035 sg. Fermentation will eventually finish, given time and warm temperatures. "

It seems like a good yeast to try to halt mid-ferment like this.

I would make sure you take measurements after two days to see how far its fermented. I know that a lot of my beers are essentially done after 2 days. Potassium sorbate will kill the yeast, thats why its used before backsweetening. I use it to backsweeten my apfelwein. I use it just in case, wouldnt want any accidents to happen because the yeast woke up.

I'd second the plan to kill the yeast. Are you kegging it?

I know that even in the fridge, both beer and wine yeast bottles of ginger ale/root beer continued to carb. I'd make sure to drink the bottles within 3 months if you don't want your whole fridge to be covered in glass shards. And be careful opening them (over a sink). One bottle shot 90% of its contends out of the bottle from the excessive carbonation.

Hmmm, It seems to me you would have to think "Dessert wine" in this case. I would use only the amount of sugar (maltose/sucrose/fructose, etc) that it takes to get your desired % alcohol, let that completely ferment and flocculate, then proceed with racking, chilling, potassium sorbate/sodium benzoate addition, backsweetening and then bottling/kegging followed by more chilling. If you're going to save these for some time however, you should at least cork or keg (Or bottle them in plastic or some expanding medium).

Potassium Sorbate will NOT kill yeast, it will not even stop an active fermentation. I beleive it is used mainly to keep dormant yeast from starting up again.

Lactose may be an option and would probably lend a little creamy flavor to the rootbeer, maybe a cross between cream soda rootbeer ale, but then you would want to also add sodium metabisulfite or potassium metabisulfite to inhibit the wild yeast because I believe wild yeast WILL ferment lactose.

Keep on brewing my friends

This will only be my 3rd batch. I do not have a keg or anything like that to put it in. The problem with flat out killing the yeast before bottling is it will be flat. I need to carb them in the bottles.

Hmm... I think I'll try just making a small batch of 6 or 12 and drinking them quick for a test run.

There is NO killing of yeast when bottling, (see above). Man I hate when my friends get killed.

Hmmm...Interesting idea with the lactose. I'd like to try that sometime. Starting a search to see if anyone has done it...