I was under the impression that Orval filtered out their house yeast and added Brett at bottling, but I have a starter going with some Orval dregs and now I’m not so sure. I stepped it up last week and now the starter is really roaring along. It has a huge frothy krausen, and is pumping out quite a bit of CO2. It smells Bretty and fantastic (apple/pineapple/cherry), but it definitely looks more like a Sacc fermentation. Either this is a mixed culture, or it’s the world’s most vigorous Brett strain.
Does anyone know if there’s Saccharomyces in Orval dregs? Anyone make a starter from Orval before? I was planning on pitching this along with some US-05 in a lambic-style brew, but if there’s already some Saccharomyces in this culture, I’ll probably pitch the whole starter into primary.
Main yeast is sacch, bottle yeast is brett, but if you make a starter from the bottle, it’s very well possible that the remaining sacch in the bottle multiplies much quicker than the brett.
I know if left unstirred/shaken a starter from Orval dregs will form a pellicle. With oxygen brett will form a krausen and look similar to a sacc strain.
Orval is not filtered but centrifuged. I would imagine the vast majority of yeast in the bottle is brett. I’ve seen a few people plate out Orval dregs and find pedio as well.
Fermentation
Orval pitches the Bastogne yeast for primary at about 3million cells/ml wort which lasts about a week or so at quite a cool temperature in 60-62F. They then spin most of the primary yeast out and adds the Brett (B. Brux) in secondary at 1000-5000 cells/ml. It stays in this ‘holding’ tank for about 3 weeks at 56F. Let the beer stay in the sencondary and then add the dry hops for the final week.
Bottling
The beer is now polished (centrifuged/ ‘filtered’) which leave it basically clean. They they repitch both yeasts at the same rate they pitched before which will have the following make up:
Main fermentation yeast : 3 millions cells/ml
Brettanomyces : 1.000 to 5.000 cells/ml