I have recently made a Bavarian Wheat that all my "co-drinkers" liked quite a lot. I have fermented that pretty cold (18C/64F), since I don't like these beers when they are overly estery and tasting to much banana-like. Now I want to use the same malt-bill and turn it into a Belgian Wit just for kicks. I was going to use White Labs WLP400 (Belgian Wit) for it. Which fermentation temperature would you use for that in comparison to the Bavarian Wheat?
According to Zainasheff in "Brewing Classic Styles" (for Belgian Wit):
Begin fermentation at 68F (20C) slowly raising the temperature to 72F (22C) by the last third of fermentation.
I'm guessing that part of that is to clean up diacetyl and the like. Most of the yeast flavor happens in the first 72 hours of fermentation. That's quite a bit warmer than what he recommends for the German wheat beers, but that also makes sense, Belgian beers having a bit more "funk" than Germans.
The Belgian Wit Ale yeast is a low producer of phenols but fermentation temperatures on the higher end of the yeasts range will produce more of the spicy phenol characteristics. I made a wit about a month ago and fermented at about 66 and the yeast character turned out relatively low compared to the spice and orange peel I added. I would stay around 66-68 for a good fermentation. Actually when using Hefeweizen yeast the lower the fermentation temp the more fruity esters you will produce. The banana character increases as the temperature increases along with the spice phenols.