Fruit beer: should I allow it to ferment out completely?

Question

I have a wheat beer in secondary that has been on 5 lbs of strawberries for 6 days. The flavor is phenomenal right now, just perfect. The strawberries continue to ferment actively, and I want to make sure I don't miss a window where the flavor changes due to allowing the strawberries to ferment out completely.

I know from what I've read that the flavor will fade over a short time, even if the flavor is strong right now. But I don't expect this brew to stick around for long anyways (i.e. less than a month). I want to capture this overwhelming fresh strawberry flavor while it lasts. I should mention that the strawberry flavor isn't so much a "sweet" flavor, but more of a "fresh" flavor as you would get if you stuck your nose into a freshly picked bucket of strawberries and breathed deeply for a few minutes.

I used German ale yeast (Wyeast 1007) and have been fermenting cool for both primary and secondary, at around 58° F, with a 3-day diacetyl rest prior to racking onto the strawberries in secondary. (OG: 1.066 ; FG prior to racking to secondary: 1.011.) This yeast does really well at low temperatures, but it did take a few days before the strawberries started to visibly ferment. At six days the fermentation is pretty vigorous.

Should I keg this now when I think the flavor is at it's peak or should I let the strawberries ferment out completely? What would be the advantages and/or disadvantages of allowing it to finish fermenting the fruit?

NOTE: Since I am kegging this rather than bottle conditioning, I don't have to be concerned about fermentation continuing in the bottle and potentially causing bottle bombs. Any advice people can give me on this would not apply if I were bottle conditioning.

Answer 1

I'd let it complete. You're not going to lose strawberry flavor by letting it ferment all the fruit. The sugar will attach the sugar from the berries; the flavor compounds will remain intact.

Also, even if you keg it now - racking it off the fruit pulp - it will continue to ferment the berry sugar in the keg. The yeast and the fruit's naturally-occurring pectic enzymes have likely already turned the berries to mush and released the berry juice into the beer. If you rack, you'll be pulling that berry juice along with the beer, and it will continue to ferment in your keg. So, I think it's going to finish fermenting whether you rack now or let it finish in the fermenter.

If you wanted it to stop fermenting and leave some unfermented berry juice, you'd have to cold crash and add sorbate, like winemakers do. That's a whole topic in and of itself.

One last thing - As a slight aside, I've found that adding fruit to beer causes the fruit beer to taste drier than the base beer. Even though the same amount of unfermentable malt sugars remain, the addition of simple sugar from the fruit, when fermented out, makes for a thinner, drier beer. This time of year I find that to be pretty refreshing, actually.

Answer 2

KEG IT NOW! I make a strawberry wheat too and the beauty of kegging is to not worry about the extra ferment. If you were bottling then you have the right idea you'd have to let it go.

When I make mine I keg it when its at its peak. I usually make that beer in prep for my wife b-day which happens in late July. I plan it just right to ferment the beer, condition a bit with strawberries, then keg it and drink the whole thing at one party.

If it tastes perfect now I say keg it. Chill it below the level of activity for the yeast and you are good to go.

If I was going to package the beer and hold it for a while I'd be concerned about the unfermented sugar.

Answer 3

What advantages/disadvantages would there be if one would filter it (if necessary) at its peak after a two day crash?

I'm planning on a low gravity, 1.045 beer. 3 day primary, 5-6 days (or less if possible) on a berry in season.

It'll be a raspberry wheat beer. Any advice on mash temp and mineral profile?