Thanks again for all the advice everyone. I've done a bit of research over the last few days and think I may have found the main (probably not only) cause of my problems - pitching rate.
On the Wyeast website I found:
High pitch rates can lead to:
- Very low ester production
- Very fast fermentations
- Thin or lacking body/mouthfeel
- Autolysis (Yeasty flavors due to lysing of cells)
The first 3 of these points describe my experience very well.
Also, I was clearly overpitching these batches. I was pitching ~0.75 million cells / °P / mL (~9.25 million / mL for average weissbier) instead of 0.35 - 0.55 million cells / °P / mL (4 - 7 million / mL for average weissbier). These recommended rates for weissbiers were obtained from the "Yeast" book (White and Zainasheff), pro brewer tips in BYO magazine (
http://byo.com/grains/item/329-brewing-with-wheat-tips-from-the-pros) and email conversations with Wyeast (
https://www.homebrewersassociation.org/forum/index.php?topic=12789.20;wap2) and are for high viability and vitality cultures (such as a lab culture or well prepared starter). I remember reading a thread by Carnie where he wanted to underpitch his weissbiers. It turns out he was totally on the right track.
So while I'll probably attempt some of the mash schedules discussed here some time in the future, I think the first step for me is to pitch a more suitable amount of yeast which should help a great deal in terms of ester and phenol production and mouthfeel. According to the Yeast book, it may also reduce the amount of sulphur produced as well.
PS Just to be clear, I never wanted to accentuate either the banana or clove, I wanted a balanced profile. The problem was I was getting
no profile at all.