Solera

For the traditional Solera process used in sherry, vinegar, and brandy production, see the Wikipedia article on Solera. In beer, particularly sour beer, a single stage Solera process has been discovered to be a reliable and easy way to continuously make sour beer.

The process of using a solera method in sour beer brewing is traditionally filling a single fermenter with a sour beer, and every 6-12 months taking about a third of the beer out for packaging. That volume is replaced with new beer or wort. This method provides the brewer with an "everlasting" sour beer that takes less time to age because of the blended components. Over time the beer can continue to develop and change, and the brewer has the option of trying to steer the beer by altering the recipe for the wort or beer used to refill the solera. As a rule of thumb, the larger the fermenter the better. This will allow for larger seasonal pulls from the solera, thus producing more beer.

Articles on Solera

• Starting a Solera, by Ed Coffey on HBT. This is a great article on what a solera is, and how to start one for sour beer.
• Michael Tonsmeire has several great articles on Solera. Some noteworthy articles:
  • Sour Solera Beer Barrel
  • Second Pull Wine Barrel Solera - touches on the yeast autolysis issue.
  • Interview with BasicBrewing on Solera, and Solera Average Age Spreadsheet.
• Farmhouse Beer Blog, Outside the Box Solera - Details on Sherry solera production, and how it relates to beer production.
• Adam Kielich's blog on small batch Solera and blending pulls to make a Gueueze.
• Dan Pixley's solera project over the last 3 years in video playlist format.

In addition, see the Blogs Wiki page for blogs that may contain more articles on solera.

Yeast Autolysis

Yeast autolysis is the rupturing of dead yeast cells, and produces meaty or rubbery off flavors . When it comes to sour beers, Lambic producers often let their beers age in barrels on the trub for up to four years without effects of off flavors from yeast autolysis. The theory is that the Brettanomyces will metabolize the off flavor compounds produced by the bursting Saccharomyces cells, and use them as nutrients . Therefore, many people have reported that they have successfully avoided yeast autolysis in solera projects, as well as just allowing sour beer to remain in the primary fermenter for the entirety of it's aging. However, as the solera ages, trub build up can eventually be a problem. Will Meyers of Cambridge Brewing Company reported an eventual autolysis issue with his solera .

Whether or not the brewer elects to refill the solera with wort or fresh beer can also potentially play a role in yeast autolysis issues eventually creeping up in a solera. Adding wort will create a thicker trub, which could lead to autolysis issues faster. In either case, theoretically these issues can be avoided. One method for avoiding off flavors from yeast autolysis is to rack some of the trub out of the solera when the seasonal pulls are taken. Another method is to rack the solera to another vessel once a year or every other year. Once removed from the trub, the Brettanomyces should be able to clean up the off flavors over time.