So after three and a half years of research, writing, and editing, American Sour Beers is finished!... sort of. Despite my best efforts there were a few questions I was unable to answer satisfactorily. u/hirschb suggested I start a thread about them. So maybe you can help me answer my questions, and I can try to help answer any questions you might have that weren't covered in the book!
Hopefully they'll be a second edition down the line, never too early to start noting areas for improvement! I also posted an errata page, just a few typos and location errors so far (not bad for 400 pages).
My 5 lingering questions:
1. Why does Brett seem to produce more of it's funky character during bottle conditioning than in a fermentor? Is the pressure preventing volatile phenols from escaping? Does the CO2 pressure alter the biological pathways? Does the dissolved CO2 itself (carbonic acid) play a role? Someone came up to me at NHC and noted that their sours seem to have gotten less funky after moving from sea level to 10,000 ft.
2. What factors determine how much lactic acid Lactobacillus produces (in addition to adequate fermentable carbohydrates). It seems like the results with some strains are wildly different. I've never had luck with White Labs L. delbrueckii (even without competition), but it sounds like some people have used it to produce very tart beers.
3. What exactly causes poor head retention is sour beer. The low pH? Protein degradation by microbes? Low hopping rate? (I suspect the answer is a combination of these things, depending on the method).
4. Why do barrel-aged beer tend to taste more lactic than sour beer fermented in impermeable fermentors? Is it sub-threshold acetic acid boosting the overall perception of acidity? Or is there really more lactic acid produced thanks to micro-oxygenation or another factor.
5. Why do sour mashes exposed to the air often become butyric (vomit-rancid butter)? As far as I've read the butyric acid production is always anaerobic.
Citations preferred over conjecture when answering.
Hopefully they'll be a second edition down the line, never too early to start noting areas for improvement! I also posted an errata page, just a few typos and location errors so far (not bad for 400 pages).
My 5 lingering questions:
1. Why does Brett seem to produce more of it's funky character during bottle conditioning than in a fermentor? Is the pressure preventing volatile phenols from escaping? Does the CO2 pressure alter the biological pathways? Does the dissolved CO2 itself (carbonic acid) play a role? Someone came up to me at NHC and noted that their sours seem to have gotten less funky after moving from sea level to 10,000 ft.
2. What factors determine how much lactic acid Lactobacillus produces (in addition to adequate fermentable carbohydrates). It seems like the results with some strains are wildly different. I've never had luck with White Labs L. delbrueckii (even without competition), but it sounds like some people have used it to produce very tart beers.
3. What exactly causes poor head retention is sour beer. The low pH? Protein degradation by microbes? Low hopping rate? (I suspect the answer is a combination of these things, depending on the method).
4. Why do barrel-aged beer tend to taste more lactic than sour beer fermented in impermeable fermentors? Is it sub-threshold acetic acid boosting the overall perception of acidity? Or is there really more lactic acid produced thanks to micro-oxygenation or another factor.
5. Why do sour mashes exposed to the air often become butyric (vomit-rancid butter)? As far as I've read the butyric acid production is always anaerobic.
Citations preferred over conjecture when answering.