Guess what? I missed this post after an arvo with some Newcastle boyz, then I had a quick meal and went over to Stephen's house to meet PistolPatch. Didn't get home 'til after dawn. (Don't worry - I walked home, but got a lift there).
I started with a lacto culture, but I didn't obtain a lot of sourness from it. Initially, I pitched the lacto culture, and put the fermentor in a fridge for 24 hours at 18C, and then pitched the German Ale yeast.
At the end of the ferment, at bottling, I added lactic acid in very small amounts (~1 ml), stirred (gently, to avoid oxidation) and sampled. Add, stir and sample: until the beer tasted balanced. I added about 25 ml total of 90% (prob 88%) lactic acid to my 25 litre batch. But, don't forget, there was already some sourness there from the lactobacillus.
Let your tongue be your guide (in may things, but in this case for the taste of the beer). Brew it to suit your taste and let everyone else adapt. You can't trust a brewer who doesn't brew for his own taste.
The recipe contained 10% Weyermann acidulated malt, 60% pils malt, 30% JW wheat malt. (Oz wheat malt works well).
I've read that adding lactic acid requires some time to integrate the acidity into the beer, and I found that with my Berlinisch weissbier. Bottled in June, and won Best of Show in the NSW State comp on 21 Oct.
You may need to brew a lot of mighty big batches b4 you use a whole litre of lactic acid. Good fun to try though!
To save Darren posting this info: a warning (from an an old Eastern Suburb Brewmaker web site)-
"Be very careful when handling acids, and try to avoid contact with the skin. You should wear gloves and eye protection when handling such dangerous compounds. "
Seth out
