A Different Kind Of Sour

September 26, 2017

Sweet, sour, salty, bitter and umami — these are the main flavor components that the human palate can detect and are the basic levels of how we enjoy what goes into our mouth. Whether it’s a well-crafted dish by a local chef, or your go-to beer, oftentimes our favorites incorporate several of these all at once. In beer, we have been well versed on the bitterness of IPAs and the sweetness of our imperial stouts, but the acid component of wild and sour beers is often misunderstood.

There are some pretty distinct differences between the main processes of adding acid components to a beer: hot side souring and barrel aging. On the surface, hot side souring is quicker but less complex, while barrel souring can take up to a few years and bring about a balanced and intricate flavor profile. The hot side of beer acidification is usually done in either the mash or the boiling vessel and will be one of the style categories at our Celebration of Funk festival on Saturday, September 30th.

At Penrose and many American craft breweries these days, we create a bright, clean acid by adding the bacteria Lactobacillus into the brew kettle for a few days in Berliner Weisses, goses and beers like Session Sour.

Our own kettle souring process includes standard brewing practices through mashing, lautering and running off, which extracts sugar to create our sweet wort. We ramp the wort temperature to boil and hold there to kill off any off flavor producing organisms that could have traveled along on the malt husks. Following a short boil, we cool down the wort to around 115 degrees Fahrenheit and pitch a strain of Lactobacillus into our boil kettle. Lactobacillus is a bacteria that can break down sugar compounds much like yeast, it turns sugar compounds into lactic acid and is the source of our sourness. After reaching the desired pH value over the course of a couple of days, we return to boil temperature to kill the Lactobacillus and resume our normal brewing process of cooling, transferring and fermentation.

In comparison to extended aging, we find the acid produced via kettle souring to be a nice component of a beer. It shouldn’t be the only flavor to focus on because it’s usually not dynamic enough to stand on its own. It can be accented nicely by hops or fruit to complement, which is why we heavily dry hop our Session Sour with Amarillo hops to add additional layers of flavor.

Kettle soured beers will have their own section at the Celebration of Funk festival to ensure you’re able to taste them side-by-side and see the acid profile that brewers can create and use as a tool in their flavor arsenal.

We hope to see you at the festival,


Kettle soured beers at the festival include Teleport Massive and Kettle Supastar from Mikerphone; Yuzu Fierce and Wari Ale from Off Color; Cascarudo and La Pina De Mis Ojos from 5 Rabbit; Here Gose Nothin’ from Destihl; A Night of Funk from Woodfour; and Blood of the Flamingo, Paloma Especial, and Agent Piña from Cruz Blanca. Tickets available here.