The second installment in our sour series is going to focus much more on the bacteria that is used to produce the wonderfully tart Gose. Today’s homebrewer has an embarrassment of options available to them in regards to types of lactobacillus, sources of lacto, and methods they can use to employ it. This was not always the case. Historically, Gose was produced using sources for lacto that were much less reliable than ours and methods that would take much longer than today.
However, the current craft beer movement has served as quite the engine for creativity in regards to sourcing new ingredients and developing exciting new methods, and smashing the two together. The growing public interest in sour styles has led to this creativity being applied to the creation of acidic beers, and what a glorious application it has been.
Lactobacillus (lacto) is one of the more commonly used souring microorganisms in brewing and is the sole bacteria used in the production of Gose. Lacto is a gram-positive thermophilic facultative anaerobe and can be heterofermentative or homofermentative. The brewing translation of that mass of jargon is: lacto is a species of bacteria that doesn’t like hops, loves warm conditions, is capable of working in the presence or absence of oxygen, some strains produce only lactic acid, and others produce multiple compounds. It is imperative to understand lacto’s characteristics and optimum fermentation environment in order to to employ it correctly.
There are countless strains of lactobacillus that exist in the world, and each has its own set of preferred conditions and traits. Lacto exists naturally in all kinds of environments and can be sourced in myriad ways. However, for the purposes of this article we are only going to discuss a few strains and a few sources.
- Lactobacillus delbrueckii – This strain is available through White Labs as WLP677, is considered to be homofermentative, and is very hop sensitive. Moderate souring potential.
- Lactobacillus brevis – This strain is available as White Labs 672/Wyeast 5223-PC, is considered to be heterofermentative, and is less hop sensitive. Strong souring potential.
- Lactobacillus buchneri – This strain is available through Wyeast as 5335, is considered to be heterofermentative, and is very hop sensitive. Moderate souring potential.
- Lactobacillus plantarum– L. plantarum is currently one of the “hot” new lacto strains. This strain is available as part of a blend through Omega Yeast Labs as OYL-605, is considered heterofermentative, and is very hop sensitive. High souring potential.
Given how ubiquitous lactobacillus is in nature, it is no surprise that there are almost as many sources for lacto as there are strains! There are a number of variables that come into play when choosing your source for this bacterium; mainly you will be considering the cost and purity of the source with some thought going towards how it will need to be treated.
- Yeast Companies– The most reliable source for pure strains of lactobacillus will always be a company that specializes in strains of yeast and bacteria that are appropriate for brewing. They will be able to ensure the purity of the strain, advise you on how to use it, and give you troubleshooting advice if something should go awry. However, this tends to be the more expensive of the sources.
- Malted Grain – Lactobacillus naturally exists on many of the grains that are used in brewing and, ergo, it is possible to culture lacto from brewing grain. However, this method requires caution, as there are other microorganisms that live on grain. Follow the recommendations that are going to be laid out in the following article on brewing practices if you want to reduce chances of spoilage. This is a very inexpensive source but it does have the potential for mishaps.
- Probiotic Pills– There are a number of homebrewers who are playing around with commercially available probiotic strains of lactobacillus for brewing. The popular l. plantarum is known to be available in its pure form as a probiotic. This is a newer method and not heavily researched. I would be conscious of the fact that you are not always aware of how much of the culture is present in a tablet and a step up starter may be required. This can be both an inexpensive and pure source but may require extra care in employing it due to small cell counts.
- Yogurt- The use of active yogurt has to be the coolest recent innovation in the sour brewing realm. Sean Burke of The Commons Brewery has been touted as the first to employ this unique source of lacto (Artist, 2015). There are a number of foods that gain their unique character from lactobacillus and yogurt is one of them. Sources say that Greek yogurt works best. You will definitely want to use a plain yogurt so that there is no flavor contribution and fat free is a must! Your beer’s head retention and flavor stability will suffer if you use a yogurt that contains too much fat. Fifth Season Gardening also carries yogurt cultures that can be used in the production of sour beers! The New England Cheesemaking Supply Sweet Yogurt (Y5) strain actually has three different strains of lactobacillus in it! Yogurt has the benefit of being cost effective and reasonably pure, but it is not clear how much lacto is being pitched when you use yogurt. Be cognizant of the fact that you want to pitch enough lacto for your fermentation.
When working with microorganisms other than standard saccharomyces cerevisiae it is imperative that one come to understand exactly what that microorganism is, how it functions in its environment, and how to best use it to achieve the results that you desire. Hopefully, after reading this article you will have a much better understanding of what lactobacillus is, what strains will work best for you, and how to source them. Keep an eye out for the next part in the series which will detail the various brewing methods one can when use when producing Gose with lactobacillus.