The Bruery – Sour Barrel Aged Beer 101 – Brewing & Yeasts

What special steps must be taken when brewing sour beers?

Tyler: Cleanliness & Sanitation. There’s a huge risk when brewing these types of beers and you don’t want them contaminating your non sour beers. The unique strains used for sour beers can wreak havoc on non sour beer production if cross contamination occurs.

How can cross contamination occur?

Jess: Cross contamination can occur by several means. It is most important to understand that these organisms, unless at a particular concentration, cannot be seen by the naked eye. If your hands, a piece of equipment or just simply the air comes in contact with a sterile surface it can become contaminated.

As far as the brewing goes, how are dark/red/blonde sours different?

Tyler: We use malts and fruit to get different colors which usually means different flavors. The style of beer usually determines how we make it, but usually we just do what we think is going to make the best tasting beer!

What sour yeast strains do we use?

Jess: We mainly use several species of Brettanomyces, but we also dabble in using strains of lactobacillus and pediococcus that are types of beer souring bacteria.

What makes the Hottenroth kind of sour different from Rueuze kind of sour?

Tyler: The malts, hops, water and yeast/bacteria used. Hottenroth is mostly a Brettanomyces and Lactobacillus fermentation, while Rueuze can have up to eight different strains in it. On top of that, Rueuze is barrel fermented & aged while Hottenroth uses stainless steel.

How does time affect these yeasts in our beer?

Jess: Most souring yeasts and bacteria are opportunistic. They either hide until the time is right to start reproducing or grow so quickly they are able to out compete other organisms for food and space. Most are also able to metabolize sugars that Saccharomyces cannot.

For example, if you look at growth curves of Saccharomyces with Brettanomyces in the same beer you will see a spike of cell concentration early on of the Saccharomyces, then once the Saccharomyces has depleted its resources Brettanomyces will kick in and start eating up what is left (which is mainly cellobiose).
If you were to throw some bacteria in the mix you would see an even more interesting shift of cell concentration of each strain as the pH decreases and alcohol content increases, producing some very interesting aromas and flavors.

How quickly can a homebrewer make a sour batch in glass or stainless steel?

Tyler: This can be done pretty fast, probably in a month or so. Bigger beers (like a Flemish Red) will benefit from age though, as Brettanomyces can take around 180 days to fully develop.