Re: Brett research and general knowledge
Sorry for the hiatus I had to finish writing up the Bretta paper over the holidays.. And attended the big beers fest in Vail, CO. a plethora of wild ales and brett funk beers to be found...
Baums I think you make two good points in the Brett IPA thread..and then expanding on them here too.
I did a search of the two patents although I didn't read the study that was done or the patent write up. I was able to find the species which were studied as they are held by NCYC depository, but it was Dekkera bruxellensis which was found to produce citric acid. Baring a discussion on the differences between the two, this was what I found. On the 3801455 patent I'm guessing it was maybe the same? Couldn't find data about the species used. Although in these patents many other species of Candida, Pichia were also all found to produce citric acid atleast in the 3733253 patent, so I'm not sure what was going on, was it a biochemical process with a medium similar to wort with these yeast in which they were able to then produce citric acid? (I'll expand on my thoughts later..)
As for lactic acid I often read about it here on these boards as being produced from Bretta, but the 25 papers or so I have, which from what I can tell is nearly every possible paper published scientifically in English or translated anyways spanning from Clausen 1904 paper up to a paper or two released in 2008, there has never been lactic acid observed to be produced by Bretta. The lactic acid is always created by Lactic Acid Bacterias? Right? Thats what I gathered.. Hence why Peter Bouckaert takes the first running of wort inoculates with lactobacillus at about 100ppm and then re-pitches into the kettle during boil. (By the way Peter went up about a week later and Brewed with Elysian Brewing in Seatle and they made an all Brett beer in this way as he always recommends) Back on track with the Lactic acid. As it has not been observed, this may be due to I also never remember any of the studies actually monitoring for lactic acid production by bretta only acetic acid production. So maybe it has not been observed since it has not been looked for. Anyone remember differently?
As for citic acid production.. this is a interesting idea. Many people are noticing the citrus flavors coming through in brett beers. Even Peter Bouckaerts hinted at it. That would would be a very skilled palate as New Belgium has daily taste panels and with his experience he would be one of the most skilled tasters trained to look for such flavors.
Also on this note, while at Avery's in Boulder, CO. last week having at look at Brabant before all the barrels are blended together and readied for bottling Andy the barrel aging guy wheeled out "Bad Sali" They have a barrel that is producing amazing aromas/flavors. They are taking their Salvation golden strng and barrel aging it. On first taste I was amazed at the Orange Bomb flavors as i instantly blurted out. I have never had a sour beer taste this amazing before. Days earlier I had just had Santification, Consecration, Temptation from Russian River, along with Cerise Casee from Cambridge brewing, New Belgium has produced a speacial La Folie for bottlewoks with Lambicus this time around, and none of those while some having some lemon zest and others stronger horsy barnyard had this amazing orange citrus flavor. So is citric acid being produced by Bretta? I think that will become part of a parameter in my upcoming masters project which is taking shape.
On that note I would like to present what I have come up with as my proposed masters research project. These projects are only supposed to encompass about 2-3 months of research and lab work (The usual UK masters doesn't do the large thesis like in the US it is more geared to getting you skilled to enter the work place so they do "Masters Dissertations"or projects instead to finish out the Masters degree) so I may be getting in over my head here and this could be cut back but here is my hopes..
First, I plan to look into is propagation of Brettanomyces for primary fermentation.
Starting possibly from single colonies streaked or kept on slants, then grown up into vial tubes, then propagated into 500mL Erlenmeyer flasks always with a standard stock solution of sugars and nutrients similar to wort.
The variables I will be looking into are:
-Optimal dissolved oxygen levels/aeration rates for cell biomass production with monitoring acetic acid production.
-Also looking at with or without the use of a stir plate/agitation on cell biomass and acetic acid production.
-Optimal pH and Temperature range when propagating.
-Looking at cell viability while propagating and the time necessary till a second step is needed in order to get cell counts high enough for pitching into a primary fermentation.
-Basically the optimal parameters for propagating up Brettanomyces.
Second, I plan to look at pitching rates of Brettanomyces when used for primary fermentation.
Multiple strains of Brettanomyces being pitched at multiple cell counts per mL or wort, grown up using the optimal conditions found previously in the study. The fermentation would be from wort brewed up on the 2hL pilot plant we have at the University. A completely anaerobic fermentation conducted in 20L batches.
The variables I will be looking into are:
-Days till fermentation is complete.
-Attenuation rate as a primary fermenter.
-Optimal fermentation temperature.
-Looking at any lag phases due to possible observance of Cutsers effect and how the phenomenon is possibly over come due to pitching rates or glucose levels...during a primary fermentation.
-Viability of Brettanomyces once fermentation commences.
-Glucose consumption and ethanol production in comparison with acetic acid production.
-I will be looking for an optimal Brettanomyces fermentation, the reaction of each yeast strain as a primary fermenter, possibly playing around with the amount of fermentable sugars available for an optimal clean fermenation, keeping acetic acid production low as possible and attaining the highest level of ethanol production.
Third, I plan to look at the aroma/flavor compounds being produced being during a Brettanomyces primary fermentation.
It is already well known about the production of ethyl acetate, ethyl lactate, lowered levels of isoamyl acetate, ethyl caproate, ethyl caprylate, ethyl caprate, 4-ethyl phenol, 4-ethyl guiaicol...
I will conduct multiple mini ferments (20L) under the optimal conditions found in the earlier experiments I conducted and then see what kind of compounds each strain is producing by running Headspace GC on each mini ferment. Along with testing bottles donated from Vinnie Cilurzo (Supplication) and Avery (Avery 15). I will be looking for possible esters which have net yet been reported due to a Brettanomyces fermentation or the possible lack of production when used as a primary fermenter.
So now any one see any ways I can tweak this?
As you can see in the end I'm really interested in trying to also discover compounds which have not been observed in Bretta spp. fermentations yet. When talking with Vinnie of Russian River we both felt there were un-known compounds/esters being produced during the fermentation with Bretta spp. Hence his giving me a bottle for research purposes. I also got a Avery 15 for research too. None of this work is underway yet as I'm re shaping and re- writing. I will work the citirc acid in as said earlier too.
So if not all of this something from this will be conducted.. Oh yeah and White Labs 3 varieties will be used plus I'm asking Chris White if they have more as they mention it at the bottom of the page that they will be testing more. Wyeast has teh brux and the lambicus which i will also try to include in and that would make 5 so I may acquire more but at least two of each (brux, lambicus, anomalus(claussenii) would be nice. If anyone has a unique culture I would be interested in working out a way of shipping it to Edinburgh, Scotland and I don't mind covering the cost obviously.