GigaYeast, Inc. http://www.gigayeast.com/
Advise on Culture Usage
Use info for our GB110, GB144, and other & upcoming pitches.
As you have learned by now, all pitches, whether they are ale/lager/Belgian yeasts, Brett, Lacto, Pedio behave markedly differently based on temperature, oxygenation, carbohydrate & protein content (from wheat vs. barley vs. rye etc..), and IBUs in the wort. As a long time home brewer I learned that it is easy to brew a good IPA or Stout, but more difficult to make lagers, and more so to make a convincing sour. As a microbiologist I know that cultivating bacterial strains is generally easier than growing yeast, so I’m a bit surprised with the complexity of brewing a good sour. There is no simple short answer solution, but FYI some strains do not play well together. At any rate, Lacto doesn’t do well with IBUs present, and higher temperatures (80F – 98F) usually improve lactic acid production over standard brewing temps. Lacto and Pedio also don’t need much/any oxygen, and some strains don’t sour well when oxygen is present. As a result, from a home brewer’s perspective it may be easier to pitch Lacto into the still-warm sparged wort and let it sour for 24h – 48h before boiling. That gets around IBU sensitivity too. The boil then kills the bacteria and lets the yeast grow in peace.
Many Lager and Ale Saccharomyces strains ferment slower if the wort is already acidic, and may need more oxygenation than for a non-sour beer. Belgian strains generally tolerate sour worts a bit better, but I have only tested a few strains so don’t know if this is usual or I was just lucky in picking strains.
Brett seems to just chug along regardless of fermentation conditions, and will metabolize many sugars that Saccharomyces can not use, regardless of oxygen levels. That is part of the reason Brett can “over carbonate” a beer, especially over several months. Anyway, don’t know if that cleared up or clouded questions you may have. At GigaYeast we are still gaining knowledge on the full metabolic profiles of our Lacto and Brett strains, and will post the info as it comes along.