Great feedback guys. I certainly don't have all the answers, but I'll try to respond.
@dantheman13
I'm souring the wort with lactobacillus purely for the lactic acid. Once an appropriate level is achieved I'll pasteurise to lock in that level of sourness. Also, I'll probably inoculate with the lactobacillus found on raw grain, which could also introduce other organisms that I don't want in the final beer .
@metic
I had the same thoughts about pitching rates. I think that, as with saccharomyces cerevisiae, the growth phase is important with Brettanomyces. This study discusses the effects:
3.1 Impact of growth phase in the nonculturable B. bruxellensis population
and 4-ethylphenol production
http://run.unl.pt/bitstream/10362/10986/1/Fernandes_2013.pdf
In summary, cells produce 4-ethylphenol (4EP) at all stages, but when there is a long lag time (time between pitching and cell growth) there is a decrease in overall 4EP production. Cells in the exponential phase, as well as healthy stationary cells (after lag phase and growth phase) are effective producers of 4EP.
So it seems that pitching rate is important, and that it is important to create healthy cells that are adapted to their environment, just as with saccharomyces. When I mentioned ale pitching rates, I guess I mean relative to the gravity after primary fermentation. I use usually use
http://www.brewersfriend.com/yeast-pitch-rate-and-starter-calculator/
to determine my pitch rates.
In terms of the right conditions for growth, somewhere around 25C seems to be a good temperature (higher might be better, but that's pushing into unconventional territory), and I don't have enough experience with dextrinous/starchy worts, or Brett, to know if two months is enough time for fermentation, but and if I can optimise the conditions I'm certainly giving the yeast the best chance.
My thoughts are that traditional lambic fermentations take such a long time as the conditions for Brett aren't ideal at the outset, and it takes time for the (potentially) unhealthy Brett to produce the enzymes to produce 4EP & 4-ethylgluaiacol (4EG).
If I can optimise the conditions from the outset by
a) providing a starchy wort (which saccharomyces can't process, and will be available for the Brett after primary fermentation finishes)
b) providing an abundance of 4-vinylgluaiacol (4VG) & 4-vinylphenol (4VP) and relatively little ferulic acid (which inhibits Brettanomyces growth, and which weizen yeast converts to 4VG & 4VP)
c) providing hydrocinnamic acids (including ferulic) for the weizen yeast to convert by using an acid rest at 44C
d) providing oxygen to allow initial growth (but limiting oxygen thereafter)
e) keeping the temperature around 25C
f) keeping ethanols levels relatively mild (ethanol inhibits growth, with growth ceasing above 15% v/v)
I initially thought that pH played a big role, but unless the pH is <3.5 I think it makes little difference, which makes sense as (from memory) Orval isn't very acidic yet it has definite Brett characteristics.
http://www.researchgate.net/publica...n_red_wine_making/file/79e4151278ac1f0594.pdf
Effect of free SO2 at pH 3.5 on the conversion of p-coumaric acid into 4-ethylphenol
In summary, low pH = higher levels of SO2 which increase the inhibitory effects of benzoic and sorbic acids.
I've also thought about beers that are 100% Brett fermented and why they don't end up especially phenolic. I'm guessing its because Brett isn't effective at converting hydrocinnamic acids (including ferulic) into 4VG & 4VP, but I don't have the science to back that up.
As you point out, whether this turns out pleasant or not is a whole other story. Science aids brewing, but in the end it's your tastebuds that decide!